NBS

PUBLICATIONS

A 11 IDE 7 E T M

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Institute for Computer Sciences and Technology

NBSIR 87-3674

Draft Stable Implementation

Agreements for Open Systems

Interconnection Protocols

NBS Workshop

for Implementors of

Open Systems Interconnection

Version 1 Edition 0

October 1987

DRAFT STABLE IMPLEMENTATION AGREEMENTS

Based on the Proceeding of the

NBS/OSI Implementor’s Workshop

Plenary Assembly Held October 9, 1987

National Bureau of Standards

Gaithersburg, MD 20899

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS — QC

100

- U 5 6

87-3674

1987

C • 2

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Institute for Computer Sciences and Technology

NBSIR 87-3674

DRAFT STABLE IMPLEMENTATION

AGREEMENTS FOR OPEN SYSTEMS

INTERCONNECTION PROTOCOLS

NBS Workshop

for Implementors of

Open Systems Interconnection

Research Information Center

National r>ureau of Standards

Gaithersburg, Maryland 20899

A) BSc

QCtoo

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m.,

1921

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Version 1 Edition 0

October 1987

DRAFT STABLE IMPLEMENTATION AGREEMENTS

Based on the Proceeding of the

NBS/OSI Implementor’s Workshop

Plenary Assembly Held October 9, 1987

National Bureau of Standards

Gaithersburg, MD 20899

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Acting Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Table of Contents

1. GENERAL INFORMATION 1 1.1 PURPOSE OF THIS DOCUMENT * 1 1.2 PURPOSE OF THE WORKSHOP 1 1.3 WORKSHOP ORGANIZATION 1

2. SUB NETWORKS 1 2.1 LOCAL AREA NETWORKS 1 2.1.1 IEEE 802.2 LOGICAL LINK CONTROL 1 2.1.2 IEEE 802.3 CSMA/CD ACCESS METHOD 1 2.1.3 IEEE 802.4 TOKEN BUS ACCESS METHOD 1 2.1.4 IEEE 802.5 Token Ring Access Method 3

2.2 WIDE AREA NETWORKS 4

2.2.1 CCITT RECOMMENDATION X.25 4

2.3 PRIVATE SUBNETWORKS 4

2.3.1 PRIVATE SUBNETWORKS' 4

3. NETWORK LAYER 1 3.1 INTRODUCTION 1 3.2 SCOPE AND FIELD OF APPLICATION 1 3.3 STATUS 1 3.4 ERRATA 1 3.5 CONNECTIONLESS -MODE NETWORK SERVICE (CLNS) 1 3.5.1 Provision of CLNS Using ISO 8473 1 3.5.2 Agreements on Mandatory Protocol Functions .... 2

3.5.3 Agreements on Optional Protocol Functions .... 2

3.5.4 Subnetwork Dependent Convergence Function .... 2

3.6 CONNECTION-MODE NETWORK SERVICE (CONS) 2

3.6.1 Provision of CONS Using X. 25/PLP- 1984 3

3.6.2 Subnetwork Dependent Convergence Protocol .... 3

3.7 ADDRESSING 4

3 . 8 ROUTING 4

3.8.1 Static Routing 4

3.8.2 End System to Intermediate System 4

3.9 MIGRATION CONSIDERATIONS 5 3.9.1 X. 25-1980 5

3.10 CONFORMANCE 5 3.11 TEST REQUIREMENTS ..... 5

4. TRANSPORT 1 4.1 INTRODUCTION 1 4.2 SCOPE AND FIELD OF APPLICATION 1 4.3 STATUS 1 4.4 ERRATA 1 4.5 TRANSPORT CLASS 4 1 4.5.1 Transport Class 1 4.5.2 Protocol Agreements 1 4.5.2.

Rules for Negotiation 1 4. 5. 2.

TRANSPORT CLASS 4 SERVICE ACCESS POINTS OR

SELECTORS 3

iii
4. 5. 2.

Retransmission Timer . . 3

4. 5. 2.

Keep-Alive Function . . 4

4.6 TRANSPORT CLASS 0 ..... ........ 6

4.6.1 Transport Class 0 Overview .... 6

4.6.2 Protocol Agreements ..... 6

4.6.2.

TRANSPORT CLASS 0 SERVICE ACCESS POINTS ... 7

4.6.3 Rules for Negotiation 7

3. UPPER LAYERS . 1 5.1 INTRODUCTION 1 5.1.1 References . 1 5.2 SCOPE AND FIELD OF APPLICATION 1 5.3 STATUS 2

5.4 ERRATA . 2

5.4.1 ISO Defect Reports 2

5.4. 1.1 Session Defects . 2

5.5 ASSOCIATION CONTROL SERVICE ELEMENT ............ 2

5.5.1 Introduction 2

5.5.2 Services ..... 2

5. 5. 2.1 ACSE Services 2

5. 5. 2.Use of Presentation Layer Services 3

5.5.3 Protocol agreements 3

5. 5. 3.1 Application Context 3

5.6 PRESENTATION ..... 4

5.6.1 Introduction 4

5.6.2 Services ....... 4

5.6.2.Presentation Services 4

5. 6. 2.

Use of Session Layer Services 5

5.6.3 Protocol Agreements ... 5

5. 6. 3.1 Transfer Syntaxes 5

5. 6. 3.

Abstract Syntaxes 5 5. 6. 3.

Presentation Context Identifier 5 5. 6. 3.

Mode-selector Position in SET 6

5. 6. 3.EXTERNAL Type ...... 6

5. 6. 3.Default Context ....... 6

5. 6. 3.

P-Selectors 6

5.6.4 Presentation ASN.l Encoding Rules 6

5. 6. 4.1 Invalid Encoding ... 6

5. 6. 4.Protocol-version, Presentation-requirements . 6

5.7 SESSION 7

5.7.1 Introduction 7

5.7.2 Services 7 5.7.2.

Session Services 7

5. 7. 2.

Use of Transport Services ... 7

5.7.3 Protocol Agreements 8

5.7.3.Concatenation 8

5. 7. 3.Segmenting ............ 8

5. 7. 3.Reuse of Transport Connection ........ 8

5. 7. 3.Use of Transport Expedited Data 8

5. 7. 3.Use of Session Version Number 8

5. 7. 3.

Receipt of Invalid SPDUs 9

5. 7. 3.

Invalid SPM Intersections 9

iv
5. 7. 3.

P-Selectors 9

5.8 Universal ASN.l Encoding Rules 9

5.8.1 Tags 9

5. 8. 1.1 Definite length 9

5.9 CONFORMANCE 10

5.9.1 Specific ASE Requirements for ACSE, Presentation,

and Session 10

5. 9. 1.1 FTAM 10

5. 9. 1.1.1 Phase 2 10

5.9. 1.2 MHS 12

5.9. 1.2.1 Phase 1 12

5.9. 1.3 VT 13

5.9. 1.3.1 Phase 1 13

5. 9. 1.3.

Phase 2 14

5.10 TEST REQUIREMENTS 15

5.11 APPENDIX A: RECOMMENDED PRACTICES 16

5.11.1 Reflect Parameter Values 16

5.12 APPENDIX B: OBJECT IDENTIFIER: STRUCTURE AND ALLOCATION . . 20

6. ISO DIS FILE TRANSFER, ACCESS, & MANAGEMENT 1 6.1 INTRODUCTION 1 6.2 SCOPE AND FIELD OF APPLICATION 2

6.3 STATUS . 2

6.4 ERRATA 3

6.5 ASSUMPTIONS 3

6.6 PRESENTATION AGREEMENTS 3

6.7 SERVICE CLASS AGREEMENTS 4

6.8 FUNCTIONAL UNIT AGREEMENTS 4

6.9 FILE ATTRIBUTE AGREEMENTS 4

6.10 DOCUMENT TYPE AGREEMENTS 5

6.10.1 Character Sets 9

6.10.1.1 IA5 Character Set 9

6.10.1.2 8859-1 Character Set 11

6.10.2 Document Type Negotiation Rules 11

6.10.2.1 Connection Establishment 11

6.10.2.2 File Creation 11

6.10.2.3 File Opening 11

6.10.3 Relationship Between DUs , DEs and Document Types . 12

6.11 F-CANCEL ACTION 13

6.12 IMPLEMENTATION INFORMATION AGREEMENTS . 13

6.13 DIAGNOSTIC AGREEMENTS 13

6.14 CONCURRENCY 14

6.15 REQUESTED ACCESS 15

6.16 SECURITY 15

6.16.1 Optional Password Support 15

6.16.2 Access Passwords 16

6.16.3 Implementation Responsibilities 16

6.17 REQUIREMENT FOR CONFORMANT IMPLEMENTATIONS 16

6.17.1 Interoperable Configurations 16

6.17.2 Relationship to ISO 8571--The FTAM Standard ... 17

6.17.3 Requirements for Document Type Support 18

6.17.4 Initiators 18

v
6.17.5 Responders . . 19

6.17.6 Senders 21

6.17.6.1 Initiator Senders 21

6.17.6.2 Responder Senders . 21

6.17.7 Receivers ...... . 22

6.17.7.1 Initiator Receivers 22

6.17.7.2 Responder Receivers ..... 22

6.17.8 Minimum Ranges 23

6.18 IMPLEMENTATION PROFILES 26

6.18.1 General Requirements for the Defined Implementation

Profiles 26

6.18.2 Use of Lower Layer Services 27

6.18.3 Document Type Requirements for the Defined

Implementation Profiles 27

6.18.4 Parameters for the Defined Implementation Profiles 28

6.18.5 Parameter Ranges for the Defined Implementation

Profiles ..... .... 29

6.18.6 File Attribute Support for Implementations .... 29

6.19 PROVISION OF SPECIFIC FUNCTION . ..... 31

6.19.1 Implementation Profile T1 : Simple File Transfer . 31

6.19.2 Implementation Profile T2: Positional File Transfer 31

6.19.3 Implementation Profile T3: Full File Transfer . . 32

6.19.4 Implementation Profile A1 : Simple File Access . . 32

6.19.5 Implementation Profile A2 : Full File Access ... 33

6.19.6 Implementation Profile Ml: Management 34

6.20 HARMONIZATION 34

6.21 APPENDIX A: FTAM DOCUMENT TYPES 35

6.22 APPENDIX B: KNOWN ERRORS IN ISO AND CCITT DOCUMENTS ... 60

7. CCITT 1984 X.400 BASED MESSAGE HANDLING SYSTEM 1 7.1 INTRODUCTION 1 7.2 SCOPE 2

7.3 STATUS 3

7.4 ERRATA . 3

7.5 PRMD to PRMD 3

. 7.5.1 Introduction 3

7.5.2 Service Elements and Optional User Facilities . . 4

7. 5. 2.1 Classification of Support for Services ... 4

7. 5. 2. 1.1 Support (S) 5

7. 5. 2. 1.2 Non Support (N) 5

7. 5. 2. 1.3 Not Used (N/U) 6

7. 5. 2. 1.4 Not Applicable (N/A) 6

7. 5. 2.

Summary of Supported Services 6

7. 5. 2.MT Service Elements and Optional User

Facilities 6

7. 5. 2.IPM Service Elements and Optional User

Facilities 8

7.5.3 X.400 Protocol Definitions 9

7.5.3.

Protocol Classification 10

7. 5. 3.

General Statements on Pragmatic Constraints . 10

7. 5. 3.

MPDU Size 11

7. 5. 3.

PI Protocol Elements 11

vi
7. 5. 3.4.1 PI Envelope Protocol Elements 11

7. 5. 3.

ORName Protocol Elements 16

7. 5. 3.

P2 Protocol Profile (Based on [X.420]) ... 18

7. 5. 3. 6.1 P2 Protocol - Heading 19

7.5. 3.6.2 P2 Protocol - BodyParts 21

7. 5. 3. 6.

P2 BodyPart Protocol Elements 23

7.5.4 Reliable Transfer Server (RTS) 25

7. 5. 4.1 Implementation Strategy 25

7. 5. 4.

RTS option selection 25

7. 5. 4.

RTS Protocol Options and Clarifications ... 26

7. 5.4.4 RTS Protocol Limitations 29

7.5.5 Use of Session Services 31

7.5.6 Data Transfer Syntax 31

7.6 PRMD to ADMD and ADMD to ADMD 31

7.6.1 Introduction 31

7.6.2 Additional ADMD Functionality 33

7.6.2.Relay Responsibilities of an ADMD 33

7. 6. 2.PI Protocol Classification Changes 34

7. 6. 2.

0/R Names 34

7. 6. 2.PI ADMD Name 35

7.6.3 Interworking with Integrated UAs 35

7.6.4 Differences with Other Profiles 35

7. 6. 4.1 TTC Profile 35

7. 6. 4.CEPT Profile 36

7.6.5 Connection of PRMDs to Multiple ADMDs 36

7.6.6 Connection of an ADMD to a Routing PRMD 36

7.6.7 Management Domain Names 37

7.6.8 Envelope Validation Errors 37

7.6.9 Quality of Service 38

7. 6. 9.1 Domain Availability 38

7. 6. 9. 1.1 ADMD Availability 38

7. 6. 9. 1.2 PRMD Availability 38

7. 6. 9.Delivery Times 38

7.6.10 Billing Information 39

7.6.11 Transparency 39

7.6.12 RTS Password Management 40

7.6.13 For Further Study 40

7.7 INTER and INTRA PRMD CONNECTIONS ..... 40

7.7.1 Introduction 40

7.7.2 The Relaying PRMD 41

7. 7. 2.1 Relay Responsibilities of a PRMD 41

7. 7. 2.Interaction with an ADMD 41

7.7.3 Intra PRMD Connections 42

7. 7. 3.1 Relay Responsibilities of an MTA 42

7. 7. 3.Loop Suppression within a PRMD 43

7. 7. 3.Routing Within a PRMD 44

7. 7. 3. 3.1 Class Designations 44

7. 7. 3. 3.Specification of MTA Classes 46

7. 7. 3. 3.Consequences of Using Certain Classes of

MTAs 46

7. 7. 3.Uniqueness of MPDUidentifiers Within a PRMD . 47

7.7.4 Service Elements and Optional User Facilities . . 47

vii
/

DEMONSTRATION 75

7.14.1 ENCODING OF RTS USER DATA 75

7.14.2 EXTRA SESSION FUNCTIONAL UNITS 75

7.14.3 MIXED CASE IN THE MTA NAME 76

7.14.4 X. 410 ACTIVITY IDENTIFIER 76

7.14.5 ENCODING OF PER RECIPIENT FLAG AND PER MESSAGE FLAG 76

7.14.6 ENCODING OF EMPTY BITSTRINGS 77

7.14.7 ADDITIONAL OCTETS FOR BITSTRINGS 77

7.14.8 APPLICATION PROTOCOL IDENTIFIER 77

7.14.9 INITIAL SERIAL NUMBER IN S- CONNECT ........ 77

7.14.10 CONNECTION DATA ON RTS RECOVERY 77

7.14.11 ACTIVITY RESUME 77

7.14.12 OLD ACTIVITY IDENTIFIER 78

7.14.13 NEGOTIATION DOWN TO TRANSPORT CLASS 0 78

7.15 APPENDIX E: WORLDWIDE X.400 CONFORMANCE PROFILE MATRIX . 79

7.16 APPENDIX F: INTERWORKING WARNINGS 90

8. DIRECTORY SERVICES PROTOCOLS 1 8.1 INTRODUCTION 1 8.2 SCOPE AND FIELD OF APPLICATION 1 8.3 STATUS AND REFERENCES 3

8.4 Use of Directories 4

8.5 Directory ASEs , Application Contexts, and Ports 5 8 . 6 Schemas 6

8.6.1 Maintenance of structure and naming rules .... 6

8.6.2 Maintenance of object classes and subclasses ... 6

8.6.3 Maintenance of Attribute Types 7

8.6.4 Maintenance of Attribute Syntaxes 7

8.7 Classification of Support for Attribute Types 7

8.7.1 Mandatory Support 7

8.7.2 Optional Support 7 8.8 Introduction to Pragmatic Constraints 8

8.9 Pragmatic Constraints the Directory Service 8

8.9.1 Character Sets 8

8.9.2 APDU Size Considerations 8

8.9.3 Service Control (SC) Considerations 9

8.9.4 Size Limit Service Control 9

8.9.5 Priority Service Control 9

8.10 Constraints on Operations 10

8.10.1 Filters 10

8.10.2 Errors 10

8.11 Pragmatic Constraints on Attribute Types 11

8.11.1 Attribute Values 11

8.11.2 Use of Pragmatic Constraints for Strings 11

8.11.3 Attribute Types 11

8.12 Conformance 15

8.12.1 DUA Conformance 15

8.12.2 DSA Conformance 16

8.12.3 Rationale for ''Conformance'' 17

8.12.4 Directory Systems Conformance Classes 18

8.12.5 Authentication Conformance 19

8.12.6 Authentication Conformance Classes 20

IX
8.13 Distributed Operations . 20

8.13.1 Referrals and Chaining 20

8.14 Underlying Services Assumed ..... ...... 20

8.14.1 ROSE .............. 21

8.14.2 ACSE ................ 21

8.14.3 Presentation 22

8.14.4 Session ........... 22

8.15 Access Control ...... ..... 22

8.16 Authentication 22

8.17 Data Security 22

8.18 Test Requirements 23

8.18.1 Major elements of Architecture ... 23

8.18.2 Distributed DSA Mixed Mode Integration Testing . . 24

8.18.3 Search Operation 24

8.19 Errors ..... 24

8.20 APPENDIX A Definitions 25

8.21 APPENDIX B Attributes and Object Classes ........ 26

8.22 APPENDIX C The Use of ROSE 31

8.23 APPENDIX D Guidelines ........ 32

8.24 APPENDIX E Glossary 33

8.25 APPENDIX F Allignment Errata 34

8.26 APPENDIX G Open Issues Related to the Directory Standard 35

9. SECURITY 1 9.1 Definitions 1 9.2 Matrix of Security Services and OSI Layers ......... 2

10. REFERENCES 1 10.1 CCITT: Consultative Committee for International Telegraph

and Telephone 1 10.2 EIA: Electronic Industries Association ..... 2

10.3 IEEE: Institute of Electrical and Electronic Engineers,

Inc 2

10.4 ISA: Instrumentation Society of America . . ... 3

10.5 ISO: International Organization for Standardization .... 3

10.6 MAP 7

10.7 NBS : National Bureau of Standards 8

10.8 NCS : National Communications System . . 8

10.9 TOP 9

'

•

' )

' /

'

' ' '

X
List of Figures

Figure 2.1 LSAP bit pattern 1 Figure 2.2 I-Field Format 3

Figure 4.1 AK exchange on idleconnection 6

Figure 6.1 Model of file transfer/access 2

Figure 7.1 The layered structure of this implementation agreement . . 1 Figure 7.2 This agreement applies to the interface between: (A)

PRMD and PRMD; (B) PRMD and ADMD; (C) ADMD and ADMD ; and

(D) MTA and MTA 3

Figure 7.3 Interconnection of private domains 4

Figure 7.14 X.409 Definition of Privately Defined BodyParts 22

Figure 7.18 An ADMD may (b) or may not (a) serve as a relay 33

Figure 7.22 Relaying PRMD 41

Figure 7.23 Intra PRMD connections 42

Figure 7.24 MD C must know of A to route the message 42

Figure 7.25 Definition of InternalTracelnfo .... 43

Figure 7.26 Defined Actions in MTASuppliedlnfo 44

Figure 7.28 Example of a confirguration to be avoided 47

Figure 8.1 Structure of this Implementation Agreement 1 Figure 8.2 Stand-alone Directory Model 2

Figure 8.3 Distributed Directory Model 3

Figure 8.4 Access to the Directory 6

Figure 8.5 APDU Exchange 8

Figure 8.6 Logical DSA Application Environment 10

Figure 8.7 DSA Interworking 17

xi
List of Tables

Table 5A.1 Session States 17

Table 5A.2 Incoming Events 18

Table 5B.1 TABLE OF ALLOCATED OBJECT IDENTIFIERS 22

Table 6.1 Parameters for FTAM-1, -2,-3 ........ 6

Table 6.2 Parameters for NBS-6, NBS-7, NBS-8 .... 7

Table 6.3 FTAM primitive data types 8

Table 6.4. IRV Graphic Character Allocations ..... 10

Table 6.5 Interoperable configurations 17

Table 6.6 Required minimal parameter support . 24

Table 6.7 Implementation profile support requirements 30

Table 6.8 Implementation profiles (NBS) and profiles (SPAG) 34

Table 6.9 Information objects in NBS-6 37

Table 6.10 Information objects in NBS-7 42

Table 6.11 Information objects in NBS-8 46

Table 6.12 Datatypes for keys 48

Table 6.12 Information objects in NBS-9 52

Table 6.14 Basic constraints for NBS Ordered flat 56

Table 6.15 Identity constraints in NBS Ordered flat 57

Table 7.4 Basic MT service elements 6

Table 7 . 5 MT optional user facilities provided to the UA-selectable on a per-message basis 7

Table 7 . 6 MT optional user facilities provided to the UA agreed for any

contractual period of time ........ 7

Table 7.7 Basic IPM service elements 8

Table 7.8 IPM optional facilities agreed for a contractual period of

time 8

Table 7.9 IPM optional user facilities selectable on a per-message

basis 9

Table 7.10 Protocol Classifications 10

Table 7.11 PI protocol elements 12

Table 7.12 ORName protocol elements 17

Table 7.13 P2 heading protocol elements 19

Table 7.15 P2 BodyParts 23

Table 7.16 Checkpoint window size of IP 29

Table 7.17 RTS protocol elements 30

Table 7.19 PI Protocol Classification Changes for a Delivering ADMD . 34

Table 7.20 Delivery Time Targets 38

Table 7.21 Forced Nondelivery Times 39

Table 7.27 Conformant MTA Classifications 45

Table 7.29 PI Protocol Elements 49

Table 7B.1 Printable string to ASCII mapping 69

Table 7E.1 Protocol element comparison of RTS 80

Table 7E.2 Protocol element comparison of PI ............ 82

Table 7E.3 Protocol element comparison of P2 87

Table 8.1 Pragmatic Constraints for Selected Attributes. Part 1 . . . 12

Table 9.1 OSI Layers Desirable for Placing Security 3

xii
1 . GENERAL INFORMATION

1 .

PURPOSE OF THIS DOCUMENT

This document records stable implementation agreements of OSI

protocols among the organizations participating in the NBS Workshop

for Implementors of OSI. This work is considered advanced enough for

use in product and test suite development, and procurement

references

1.2

PURPOSE OF THE WORKSHOP

In February, 1983, at the request of industry, NBS organized the NBS

Workshop for Implementors of OSI to bring together future users and

potential suppliers of OSI protocols. The workshop accepts as input

the specifications of emerging standards for protocols and produces as

output agreements on the implementation and testing particulars of

these protocols. This process is expected to expedite the development

of OSI protocols and promote interoperability of independently

manufactured data communications equipment.

1 .WORKSHOP ORGANIZATION

The Workshop organizes its work through Special Interest Groups

(SIGs) that prepare technical documentation. An executive committee

of SIG chairpersons led by the overall Workshop chairperson

administers the workshop. NBS invites highly qualified technical

leaders from participating organizations to assume leadership roles in

the SIGs. The SIGs are encouraged to coordinate with standards

organizations and user groups, and to seek widespread technical

consensus on implementation agreements through international

discussions and liaison activities.

The Workshop meets four times a year at the National Bureau of

Standards in Gaithersburg, Maryland where each SIG is required to

convene a meeting. In addition, a plenary assembly of all workshop

delegates is convened for consideration of SIG motions and other

workshop business. SIGs are also encouraged to hold interim meetings

at varied locations around the world.

The Workshop is an open public forum. Registration materials,

documents, and workshop schedules are available from:

NBS WORKSHOP FOR IMPLEMENTORS OF OSI

ATTENTION: Larry Keys

Building 225, Room B-217

National Bureau of Standards

Gaithersburg, Maryland 20899
-

.
2. SUB 2.1 NETWORKS

LOCAL AREA NETWORKS 2.1.1

IEEE 802.2 LOGICAL LINK CONTROL

The following decisions have been reached with respect to this

protocol

1. Link Service Access Point (LSAP)

The IEEE 802 committee has assigned the code below to

address systems using any ISO network layer protocol. Note

that bit zero is transmitted first.

The most significant bit is bit 7, thus this bit pattern

represents hexadecimal FE.

0 1 2 3 4 5 6 7

0 1 1 1 1 1 1 1

Figure 2.1 LSAP bit pattern

2. Type and Class

Only the connectionless type 1, class 1 IEEE 802 link

service will be used.

2,1.2

IEEE 802.3 CSMA/CD ACCESS METHOD

The 48 bit addressing shall be used.

2,1,3

IEEE 802.4 TOKEN BUS ACCESS METHOD

The following options are agreed to with respect to Draft F of

token bus. An asterisk means that the option has been approved.

The absence of an asterisk means that the option has not been

approved.

/

2-1
1. Repeaters

Active Regenerative

2 . Medium

Single Cable Coax * Dual Cable Coax

3. Trunk Cable

RG-6 * RG-11 * Semi-rigid * Other 75 ohm cables *

4. Trunk Connection Unit

75 ohm tee connector

75 ohm nondirectional passive

impedance -matching tap

75 ohm directional passive impedance- * matching tap

5. Transmit Carrier Frequency

RF * Baseband

6. Modulation

Phase Continuous FSK

Phase Coherent FSK

AM/PSK *

7 . Encoding

Manchester

Duobinary *

8 . Data Rate

1 Mb

5 Mb *

10 Mb *

9. Addressing

2 octet

6 octet *

10. Connector at Station

50 ohm Male BNC Series

75 ohm Female F Series *

11. Priority (4 levels) *

12. Group Addressing *

13. Station Management

14. Broadband Channel Assignments

Forward Reverse

P 3 ' * Q

4 ' * R 4M' *

S 5 ' *

T 6 ' * U FM1 ' *

2-2
2.1.4 IEEE 802.5 Token Ring Access Method

The following implementation agreements have been reached with

respect to the IEEE Standard 802.5, Token Passing Ring Access

Method and Physical Layer specification.

o The data signalling rate shall be 4 Mbit/s

o The address length shall be 48 bits

o The message priority (PM) of the AMP data unit shall be

o The ALL_STATIONS_THI S_RING_JADDRES S shall be

X' COOOFFFFFFFF'

0 The TRR value shall be 4 milliseconds

o The THT value shall be 8. 9 milliseconds

o The TQP value shall be 20 milliseconds

o The TVX value shall be 10 milliseconds

o The TNT value shall be 2. 6 milliseconds

o The TAM value shall be 7 seconds

o The TSM value shall be 15 seconds

o The MAC Information field (I-field) sha

following limits:

Protocol limit of 4425 bytes

All stations shall support at least 2000 bytes

where the I-field is defined (in figure 2.2) as

follows

Starting Sequence I-Field End Sequence

and the

1) Starting Sequence includes: SD , AC , FC , DA, SA

2) Ending Sequence includes: FCS,ID,FS

Figure 2.2 I -Field Format

2-3
2.2 WIDE AREA NETWORKS

2.2.1 CCITT RECOMMENDATION X.25

When providing CONS, it is agreed to use X.25 as the standard

wide area network protocol. Elements of X.25 are explained in

section 3.

2.3 PRIVATE SUBNETWORKS

2.3,1 PRIVATE SUBNETWORKS

The architectures agreed upon allow the use of private

subnetworks in addition to private X.25 subnetworks. No

particular private subnetwork has been discussed.

2-4
3. NETWORK LAYER

3 .

INTRODUCTION

This chapter presents agreements for providing the OSI network

service. Also contained here are agreements on network layer

addressing and routing.

3.2

SCOPE AND FIELD OF APPLICATION

These agreements cover both connectionless -mode and connection-mode

network services.

3 ,STATUS

Completed in March 1987.

3 .ERRATA

3.5

CONNECTIONLESS -MODE NETWORK SERVICE (CLNS)

3.5.1 Provision of CLNS Using ISO 8473

ISO 8473, Protocol for Providing the Connectionless-mode Network

Service . will be used to provide the connectionless-mode network

service. The full conformance protocol will be used with the

following exceptions.

o The inactive subset for intra- subnetwork communication

will not be supported. Implementations will not

transmit PDUs encoded using the inactive subset.

Received PDUs encoded using the inactive subset will be

discarded.

o The non-segmenting subset will not be used.

Implementations will not generate data PDUs without- a

segmentation part. However, implementations will

receive and correctly process PDUs which do not contain

the segmentation part.

;

3-1
3.5.2 Agreements on Mandatory Protocol Functions

o An end system must provide a local means to control the

value to be assigned to the lifetime parameter for PDUs

which it originates.

3.5.3 Agreements on Optional Protocol Functions

o The Security parameter is not defined by these

Agreements. Implementations shall not transmit the

parameter except where defined by bilateral agreements.

o Partial and complete source Routing will not be

supported.

o Partial record of Route will be supported by

Intermediate systems.

o ISO 8473 will be followed with respect to QOS.

o The lifetime parameter is a hop count, subject to

change by human operators. The initial value is

recommended to be three times the diameter of the

network. As the PDU passes each IS, the IS subtracts

one from this field. When the field becomes zero by

subtraction, the PDU is thrown away.

3.5.4

Subnetwork Dependent Convergence Function

A subnetwork dependent convergence function (SNDCF) for operating

the CLNS over CCITT Recommendation X.25 has been agreed to. It

shall adhere to the following.

o Conform to ISO 8473 ADI.

o The default throughput class should be used if this

facility is available.

3.6 CONNECTION-MODE NETWORK SERVICE (CONS)

The following agreements concern provision of the connection-mode

Network Service.

o The definition of the CONS is as specified in ISO 8348,

Network Service Definition.

1 A problem exists with the Partial Source Routing option which can

cause PDUs to loop in the network until their lifetime expires.

3-2
o The mapping of the elements of the CONS to the elements of

the X.25 Packet Level Protocol (PLP) is as specified in ISO

8878, Use of X.25 to Provide the Connection-mode Network

Service

o The general procedures and formats of the X.25 PLP are as

specified in ISO 8208, X.25 Packet Level Protocol for Data

3.6.1 Terminal Equipment .

Provision of CONS Using X. 25/PLP-1984

The following agreements have been reached concerning the use of

ISO 8878.

o The Receipt Confirmation service will not be provided,

so the corresponding protocol elements need not be

implemented.

o The Expedited Data service will not be provided, so the

corresponding protocol elements need not be

implemented.

o Where the ISO 8208 diagnostic codes are not provided,

all Cause/Diagnostic code combinations can be mapped

to the Originator/Reason code of "Undefined"

3.6.2

Subnetwork Dependent Convergence Protocol

A subnetwork dependent convergence protocol (SNDCP) shall be used

to provide the CONS in cases where an End system may not use the

elements of the X. 25/PLP- 1984 needed to do so. This may be the

case, for example, when operating in a packet-switched network

environment which will treat as an error the use of any of the

CCITT-specified DTE facilities.

The SNDCP to be used is defined in Annex A of ISO 8878 and

referred to as the Alternative Procedures for Network Connection

Establishment and Release.

The following agreements have been reached concerning the use of

the SNDCP.

o The Receipt Confirmation service will not be provided,

so the corresponding protocol elements need not be

implemented.

o The Expedited Data service will not be provided, so the

corresponding protocol elements need not be

implemented

3-3
I

3.7 ADDRESSING

Address formats supported will conform to ISO 8348 DAD2 .

o NSAP address formats will have a hierarchical structure.

This will reduce the size of routing tables.

o If used in the Domain Specific Part (DSP) , an NSAP selector

shall be the least significant component in the hierarchy.

The NSAP selector shall not be used to preform routing; it

is simply intended to identify the network service user at

the destination end system. For those implementations using

an NSAP selector, there shall be one and only one selector

for each NSAP within the end system. All NSAP addresses

identifying a given NSAP will use the same NSAP selector

value

3 . 8 ROUTING

3.8.1 Static Routing

End systems and Intermediate systems supporting static routing

will provide a local mechanism to update and, if necessary, to

create the local routing table. Updating and consistency

checking will be performed by human operators. The algorithms

and data structures used for static routing are not specified in

these agreements. Implementors are free to perform these

functions in the manner which is most appropriate to their system

environment

3.8.2 End System to Intermediate System

Dynamic routing between End systems and Intermediate systems is

performed using the protocol described in ISO 9542, End System to

Intermediate System Routing Exchange Protocol for use in

conjunction with ISO 8473 . The following agreements apply to the

use of this protocol over LANs and point-to-point links.

1. Implementations must support any valid NSAP format. For

the purposes of the protocol, NSAP addresses are

treated simply as octet strings.

2. Implementations must support both Configuration

Information and Route Redirection Information. No

subsets are permitted.

3. All timer values must be settable using local system

3-4
4.

/

management

Use of checksums must be settable using local system

management. Under normal use, checksums will be

disabled.

5. The QOS, Security and Priority parameters should not be

used for routing. For conformance, Intermediate

systems must transmit these parameters in RD PDUs if

they are present in the data PDU which generated the

redirect. However, End systems must ignore them in

received RD PDUs.

6. Both ES and IS implementations must support the

'optimization' described in Clause A. 3 of ISO 9542 for

system initialization. Its use must be selectable

using local system management.

7. This protocol employs the same LSAP as ISO 8473.

8. The encoding of the BSNPA address follows the syntax

rules for the data link being used. On a LAN, for

example, it is a 48-bit MAC address.

3.9

MIGRATION CONSIDERATIONS

This section considers problems arising from evolving OSI standards

and implementations based on earlier versions of OSI standards.

3.9.1 X. 25-1980

Prior to X. 25-1984 migration, many public MHS and European

private MHS systems support X. 25- 1980 without the SNDCP defined

in IS08878/Annex A. Said systems are not providing OSI CONS as

defined by ISO 8348 and are therefore considered beyond the scope

of this document.

3.10

CONFORMANCE

3.11

TEST REQUIREMENTS

3-5
'

,
4. TRANSPORT

4 ,INTRODUCTION

These agreements support the integration of LANs, packet networks, and

other WANs with the smallest possible set of mandatory protocol sets,

in accordance with the other agreements already reached. Nothing here

shall preclude vendors from implementing protocol suites in addition

to the ones described in this document.

4,2

SCOPE AND FIELD OF APPLICATION

Two connection-oriented transport classed have been identified for

implementation: classes 0 and 4. Transport class 4 is endorsed for

use over CLNS and CONS. Transport class 0 is endorsed for use over

CONS.

4 ,STATUS

Completed March 1987.

4 .ERRATA

4.5 TRANSPORT CLASS 4

4.5.1

Transport Class 4 Overview

Transport class 4 is mandatory for communication between systems

using the OSI CLNS and may also be used for systems using the OSI

CONS (i.e., a private MHS , etc.).

4.5.2

Protocol Agreements

The full protocol will be available including expedited data and

negotiation at connection establishment. A disconnect request

shall be issued in response to a connect request when the maximum

number of transport connections is reached or exceeded.

4. 5. 2.1 Rules for Negotiation

o In general, the ISO rules for negotiation will be used,

specifics follow.

o All implementations will send the 16/31 window

size/sequence space in the CR TPDU. Implementations

must all provide the 16/31 ISO option. Implementations

must be able to accept the 4/7 in a CR TPDU.

o The ISO maximum TPDU size is negotiable between 128 and

8K octets, always negotiated downward. The ISO rules

4-1
are to be followed, allowing any valid size in the CR

TPDU. TPDU size negotiation is a local implementation

issue. Each vendor will decide how it is implemented

in their end system.

o The security parameter is optional and user defined in

the ISO specification. Implementations should not send

the security parameter in the CR TPDU; if received the

parameter should be ignored.

o Both transports must agree to not use checksum,

according to the ISO specifications. Requesting its

use is an implementation choice. All implementations

must be able to operate with checksum if requested.

o Use of acknowledgement time parameter is optional in

ISO 8073. If an implementation is operating any policy

which delays the transmission of AK TPDUs , the maximum

amount of time by which a single AK TPDU may be delayed

shall be indicated to the peer transport service

provider using the acknowledgement time parameter. The

value transmitted should be expressed in units of

milliseconds and rounded up to the nearest whole

millisecond.

o Throughput, priority, and transit delay are optional in

the ISO specification. Do not send in the CR TPDU;

ignore in the CC TPDU.

o User data in the CR TPDU and the CC TPDU are optional.

No implementation should send; all implementations must

be prepared to receive.

o An unknown parameter in any received CR TPDU shall be

ignored.

o Known parameters with invalid values in a CR TPDU shall

be handled as follows:

4-2
Parameter Action

TSAP id

TPDU size

Version

Protection (Security)

Checksum

Additional Options

Alternate Protocol Classes

Acknowledge Time

Throughput

Residual Error Rate

Priority

Transit Delay

Send DR TPDU

ignore parm, use default

ignore parm, usedefault

implementation dependent

discard CR TPDU

Protocol Error

Protocol Error

ignore parm

ignore parm

ignore parm

ignore parm

ignore parm

4. 5. 2.TRANSPORT CLASS 4 SERVICE ACCESS POINTS OR

SELECTORS

The TSAP selector field in the CR and CC TPDUs shall be

encoded as a variable length field and will be interpreted

as an octet string. The length of the string cannot exceed

32 octets.

4. 5, 2.Retransmission Timer

It is recommended that the value used for the retransmission

timer be based upon the round-trip delay experienced on a transport connection. The implementation should maintain,

and continually update, an estimate of the round-trip delay

for the TC. From this estimate, a value for the

retransmission timer is calculated each time it is started.

An example technique for maintaining the estimate and

calculating the retransmission timer is described below.

Further information on similar techniques may be found in

the literature [Edge 84, Jain 85, Mill 83].

The value of the retransmission timer may be calculated

according to the following formula:

In this formula, E is the current estimate of the round-trip

delay on the transport connection, w is the value of the

acknowledgement time parameter received from the remote

transport service provider during connection establishment,

and k is some locally administered factor.

t < kE + w

4-3
A value for k should be chosen to keep the retransmission

timer sufficiently small such that lost TPDUs will be

detected quickly, but not so small that false alarms are

generated causing unnecessary retransmission.

The value of E may be calculated using an exponentially

weighted average based upon regular sampling of the interval

between transmitting a TPDU and receiving the corresponding

acknowledgement. Samples are taken by recording the time of

day when a TPDU requiring acknowledgement is transmitted and

calculating the difference between this and the time of day

when the corresponding acknowledgement is received. New

samples are incorporated with the existing average according

to the following formula.

E <— E + (1 - a)(S - E)

In this formula, S is the new sample and a is a parameter

which can be set to some value between 0 and 1. The value

chosen for a determines the relative weighting placed upon

the current estimate and the new sample. A large value of a

weights the old estimate more heavily causing it to respond

only slowly to variations in the round-trip delay.

A small value weights the new sample more heavily causing a quick response to variations. (Note that setting a to 1 will

effectively disable the algorithm and result in a constant

value for E, being that of the initial seed.)

If a is set to 1 - 2

~ n for some value of n, the update can be

reduced to a subtract and shift as shown below.

E < E +

2' n (S - E)

When sampling, if an AK TPDU is received which acknowledges

multiple DT TPDUs, only a single sample should be taken

being the round-trip delay experienced by the most recently

transmitted DT TPDU. This attempts to minimize in the

sample any delay caused by the remote transport service

provider withholding AK TPDUs.

4. 5. 2.Keep-Alive Function

The Class 4 protocol detects a failed transport connection

by use of an 'inactivity timer'. This timer is reset each

time a TPDU is received on a connection. If the timer ever

expires, the connection is terminated.

The Class 4 protocol maintains an idle connection by

periodically transmitting an AK TPDU upon expiration of the

'window timer'. Thus, in a simple implementation, the

4-4
interval of one transport entity's window timer must be less

than that of its peer's inactivity timer, and vice versa.

The following agreements permit communicating transport

entities to maintain an idle connection without shared

information about timer values.

o In accordance with ISO 8073, clause 12. 2. 3. 9. a,

all implementations must respond to the receipt

of a duplicate AK TPDU not containing FCC by

transmitting an AK TPDU containing the 'flow

control confirmation' parameter.

o Implementations must always transmit duplicate AK

TPDUs without FCC on expiration of the local

window timer (see ISO 8073, clause 12.2.3.8.1).

Receipt of this TPDU by the remote transport

entity will cause it to respond with an AK TPDU

containing the 'flow control confirmation'

parameter. When this is received by the local

transport entity, it will reset its inactivity

timer. See figure 4.1.

o It is a local matter for an implementation to set

the intervals of its timers to appropriate

relative values. Specifically:

o The window timer must be greater than the

round-trip delay. See section 4.1.4.

o The inactivity timer must be greater than two

times the window timer; and should normally be an

even greater multiple if the transport connection

is to be resilient to the loss of an AK TPDU.

A duplicate AK TPDU (See Figure 4.1.) is one which contains

the same values for YR-TU-NR, credit, and subsequence number

as the previous AK TPDU transmitted. A duplicate AK TPDU

does not acknowledge any new data, nor does it change the

credit window.

4-5
w

expire

duplicate

AK

reset

AK + FCC

expire

duplicate

AK

reset

expire

AK + FCC

Figure 4.1 AK exchange on idleconnection

4,6 TRANSPORT CLASS 0

4.6.1

Transport Class 0 Overview

Transport class 0 over X.25 is mandatory (see X.400) for use in

communicating with public MHS systems operating in accordance

with the CCITT X.400 series recommendations. The purpose of the

agreements concerning transport class 0 is to allow connection to

these public services. Transport class 0 over X.25 can also be

used in communicating between PRMDs (this choice is prevalent

outside North America)

4.6.2

Protocol Agreements

Transport class 0 is a relatively simple protocol providing

little opportunity for conflicting interpretations. A few

relevant agreements follow.

o The Error (ER) TPDU may be used at any time and upon

receipt requires that the recipient disconnect the

network connection, and by extension the transport

connection.

o The allowed values for the maximum TPDU size are as

specified in ISO 8073. They are: 128, 256, 512, 1024,

4-6
and 2048

o The class 0 protocol does not support multiplexing. At

any instant, one transport corresponds to one network

connection.

o It is recommended that the optional timers TS1 and TS2,

if implemented, be settable by local system management.

Values in the order of minutes should be supported.

o An unlimited TSDU length must be supported.

4,6,2.TRANSPORT CLASS 0 SERVICE ACCESS POINTS

For communicating with public MHS systems, Section 5 of

X.410 specifies the use and format of TSAP identifiers.

4.6.3 Rules for Negotiation

The ISO rules for negotiations will be used.

;

4-7
.

.
5. UPPER LAYERS

/

5 . 1 INTRODUCTION

In this portion of the Implementors' Agreements, the NBS Upper Layers

SIG is primarily concerned with providing implementation agreements

for ACSE, and the Presentation and Session layers, so that systems

implemented according to these agreements can successfully

interoperate

5.1.1 References

All documents referenced in the Upper Layers section of these

agreements can be found in the REFERENCES section of this NBS

Implementors' Agreements document.

5,2 SCOPE AND FIELD OF APPLICATION

This section does not detail particular conformance statements for

ACSE, Presentation, and Session, since what is to be implemented in

each case depends on which Application Service Elements (ASE's) and

which functional units within each ASE are used with an Application

Process. Each ASE's SIG must specify which functional units of each

layer it requires. However, the scope of each layer is based on the

total indicated requirements of all ASE's for which there is an active

NBS SIG. The implementation agreements are not specified beyond that

scope

It is not the intent of this document to specify or reproduce

standards, but when a referenced standard is unclear or has known

defects, an attempt will be made to remedy the problem herein. Any

attempted clarification should be considered as a possible

interpretation; the ISO standard still takes precedence if there is

any conflict. The situation with respect to defects in a standard is

somewhat different; a reported defect may be technically resolved by

the appropriate international technical committee with likely approval

by the voting members pending for several months. Since relevant

defects can't be ignored in an implementation, this document will

recommend using defect resolutions which have the tentative approval

of the appropriate standards committees.

5-1
5 .

STATUS

This document is the first draft of the first stable version of the

NBS UL sig.

5 .

ERRATA

5.4.1 ISO Defect Reports

This section lists the defect reports from ISO which are

currently recognized to be valid for the purposes of NBS

conformance

5. 4.

1.1

Session Defects

ISO/IS 8326 lists the following defect reports which have

been incorporated into version 1 of Session:

004, 006, 009, Oil, 012, 013, 014, 015, 016, 017, 020.

ISO/IS 8327 lists the following defect reports which have

been incorporated into version 1 of Session:

005, 035.

5,5

ASSOCIATION CONTROL SERVICE ELEMENT

5.5.1 Introduction

This section details the implementation requirements for the

Association Control Service Element (ACSE) of the Application

layer. It is the intent of this section to follow the ISO ACSE

standards. Where those specifications are inadequate, this

section should provide the necessary information.

5.5.2 Services

5.5.2.

ACSE Services

The following ACSE service primitives are within the

possible scope of an NBS conformant system:

5-2
1. A_ASSOCIATE request

2 . A_ASSOCIATE indication

3 . A_ASSOCIATE response

4. A_ASSOCIATE confirm

5. A_RELEASE request

6. A_RELEASE indication

7 . A_RELEASE response

8. A_RELEASE confirm

9. A_ABORT request

10. A_AB0RT indication

11. A P ABORT indication

5. 5 .2,

Use of Presentation Laver Services

ACSE services will make use of Presentation layer services

in the manner defined in the ACSE Protocol specification,

Editor's IS draft.

5,5.3 Protocol agreements

Implementations shall be based on the ACSE Service definition,

editor's IS draft and the ACSE Protocol specification, editor's

IS draft.

5. 5. 3.1 Application Context

Specific Application Contexts and their names will be

supplied and defined by the appropriate NBS SIG. Other

application contexts may be defined and specified as

dictated by particular application requirements.

Optional names and specifications are outlined by each

application sig under the heading "Specific ASE Requirements

for ACSE, Presentation, and Session"; The use of these

names implies adherence to the relevant NBS implementors'

agreements for a particular application sig.

The utility of the NBS defined name (which is an OBJECT

IDENTIFIER) is left up to the application. The NBS name may

or may not be used in the ACSE APDU. The consequence of the

name is left up to the application entities and any a priori

agreements that they have. In other words, it is up to the

application whether this parameter is ignored or validated

for correctness. (Note that the consequence of this name

must also be dictated by the particular conformance test)

The UL sig recognizes that this parameter needs further

definition by the appropriate standards bodies. Therefore,

the use of this parameter for association negotiation is not

5-3
recommended at this time.

5.6 PRESENTATION

5.6,1 Introduction

This section details the implementation requirements for the

Presentation layer. It is the intent of this section to follow

the ISO Presentation Standards. Where those specifications are

inadequate, this section should provide the necessary

information.

The task of the Presentation layer is to carry out the

negotiation of transfer syntaxes and to provide for the

transformation to and from transfer syntaxes. The transformation

to and from a particular transfer syntax is a local

implementation issue and is not discussed within this section.

This section is concerned with the protocol agreements, and thus

is entirely devoted to the issues involved with the negotiation

of transfer syntaxes and the responsibilities of the Presentation

protocol

5.6.2 Services

5 .6. 2.1 Presentation Services

The following functional units are within the possible scope

of an NBS conformant system:

Presentation Kernel - This functional unit

supports the basic Presentation services

required to establish a Presentation

connection, transfer normal data, and release a Presentation connection. This is a nonnegotiable functional unit.

The Context Management and Context Restoration

functional units are not within the scope of an

NBS conformant system and need not be

supported.

The requirement that the Presentation kernel functional unit

be implemented does not imply that any of the Session

functional units for expedited data, typed data, and

capability data and the corresponding Presentation service

primitives are required to be implemented. Any service not

supported by the Session layer is also not supported by the

Presentation layer; see the section on Session Functional

Units for the possible Session functional units. The

5-4
services provided by the Presentation layer are limited by

the services provided by the Session layer as defined in the

Session service definition ISO/IS 8326 and the Session

protocol definition ISO/IS 8327.

5. 6. 2.

Use of Session Laver Services

Presentation layer services shall make use of Session layer

services in the manner defined in the Presentation Protocol

Definition, ISO 8823 Revision C.

5.6.3 Protocol Agreements

Implementations shall be based on the Presentation Service

Definition, ISO 8822 Revision C and the Presentation Protocol

Definition, ISO 8823 Revision C.

5. 6, 3.1 Transfer Syntaxes

o The following transfer syntax must be supported for all

mandatory abstract syntaxes: the basic encoding rules

for ASN.l. This syntax is derived by applying the

basic encoding rules for ASN.l to the abstract syntax

(see the Basic Encoding Rules for ASN.l, ISO 8825).

o The number of transfer syntaxes proposed is dependent

upon the recognized transfer syntaxes which are

available to support the particular abstract syntaxes

used by an Application Entity.

5. 6. 3.Abstract Syntaxes

o Several abstract syntax names may map onto a single

transfer syntax name. Note: the specific abstract

syntax names are outside the scope of this Presentation

specification and must be determined by the particular

requirements of the application.

o The ACSE abstract syntax shall always be present in the

defined context set.

5.6. 3.

Presentation Context Identifier

5-5
The presentation context identifier value shall be encoded

in no more than 2 octets.

5. 6. 3.

Mode-selector Position in SET

Whenever the Mode-selector value within either a CP-PPDU or

CPA-PPDU is normal-mode (1), it shall occur as the first

element with the SET.

5 .6. 3.EXTERNAL Type

It is assumed that "presentation layer negotiation of

encoding rules" is always in effect, and therefore clause

32.5 of the Specification of ASN.l, ISO 8824 never applies.

5. 6. 3.Default Context

If the Presentation expedited data service is required, the

default context must be explicitly present in the P-CONNECT

PPDU at Presentation connect time.

5. 6. 3,P-Selectors

Local P-selectors shall be a maximum of 4 octets. This

applies only to P-selectors in PPDUs whose receipt by an

NBS- conformant system normally results in either a P-CONNECT

indication or a P-CONNECT confirmation being issued.

5.6.4 Presentation ASN.l Encoding Rules

5.6.4.Invalid Encoding

If a received PPDU contains any improperly encoded data

values (including data values embedded within the User Data

field of a PPDU) and an abort is issued, then either a P-UABORT or a P-P-ABORT shall be issued.

5 .6. 4.Protocol-version. Presentation-requirements

Protocol-version and Presentation-requirements shall be

encoded as primitive, if encoded.

5-6
5,7 SESSION

5.7.1 Introduction

This section details the implementation requirements for the

Session layer. It is the intent of this section to follow the

ISO Session Standards to the fullest extent possible. Where

those specifications are inadequate, this section should provide

the necessary information.

5.7.2 Services

5 .7. 2.1 Session Services

The following functional units are within the possible scope

of an NBS conformant system:

Kernel

Duplex

Expedited Data

Resvnchronize

Exceptions

Activity Management

Half -duplex

Minor Synchronize

Major Synchronize

Typed Data

5. 7. 2.

Use of Transport Services

The use of Transport layer services by the Session layer

functional units listed in the previous section is as

specified in the Transport Protocol Specification, ISO/IS

8073.

5-7
5.7.3 Protocol Agreements

Implementations shall be based on the Session service definition

ISO/IS 8326 and the Session protocol definition ISQ/IS 8327.

5.7.3.Concatenation

When a category 0 SPDU is concatenated with a category 2

SPDU, the category 0 SPDU shall contain neither the Token

Item field nor User Data. If either a Token Item field or

User Data is received in such a concatenated incoming SPDU,

the receiving Session Protocol Machine has the option of

either properly processing the fields or issuing a provider

abort on the connection.

Extended concatenation is not required and can be refused

using the normal negotiation mechanisms of the Session

protocol

5. 7. 3,Segmenting

Session Segmenting is not required and can be refused using

the normal negotiation mechanisms of the session protocol.

5. 7. 3.Reuse of Transport Connection

Reuse of a transport connection is not required and can be

refused.

5.7.

3.4

Use of Transport Expedited Data

The use of transport expedited service is as stated in the

session protocol specification: if available, transport

expedited service must be used.

5. 7. 3.Use of Session Version Number

Session versions 1 and 2 are recognized. Each relevant NBS

sig chooses the version or versions of Session which it

requires for a particular implementation phase, and these

choices are documented in section 5.9.1.

Session version 2 specifies the use of unlimited user data

during connection establishment as dictated by the DAD 2 to

ISO 8327 to Incorporate Unlimited User Data. The maximum

length of user data in the CONNECT SPDU shall be 10,240

octets; if the length of this user data is no greater than

5-8
512 octets, a PGI of 193 is used, otherwise a PGI of 194 is

used.

User data shall be limited to 10,240 octets on all other

SPDUs with a PGI of 193 when version 2 of Session has been

negotiated.

5. 7. 3

.6

Receipt of Invalid SPDUs

Upon receipt of an invalid SPDU, the SPM shall take any

action in A. 4.of the Session protocol definition ISO/IS

8327 except d)

5. 7. 3.

Invalid SPM Intersections

If the conditions described in A. 4. 1.2 of the Session

protocol definition ISO/IS 8327 are satisfied, the SPM shall

always take the actions described by A. 4. 1.2 a).

Note: This means that no S-P- EXCEPTION-REPORT indications

will be generated nor EXCEPTION REPORT SPDUs sent due to

invalid intersections of the Session state table resulting

from received SPDUs.

5.7.3.

P-Selectors

S-selectors shall be a maximum of 16 octets.

5.8

Universal ASN.l Encoding Rules

5.8.1 Tags

The maximum value of an ASN.l basic encoding tag that need be

handled by an NBS- conformant implementation shall be 16,383.

This is the maximum unsigned number that can be represented in 14

bits, therefore, the maximum encoding of a tag occupies 3 octets.

5.8. 1.1 Definite length

The maximum value of an ASN.l length octets component that

need be handled by an NBS -conformant implementation shall be

4,294,967,295. This is the maximum unsigned integer that

can be represented in 32 bits, therefore, the maximum

encoding of a length octets component will occupy 5 octets.

Also, note this restriction does not apply to indefinite

5-9
5 . 9 CONFORMANCE

In order for an implementation to be in conformance with the NBS

implementors' agreements, the following rules shall be adhered to:

o A conformant implementation must be ISO conformant as well as

meet all of the requirements of this specification. All

documents referenced in the Upper Layers section shall be used as

the supporting documents for all implementations of ACSE,

Presentation, or Session. The full references for these

documents are in the REFERENCES section, and these should be used

to determine upon which specific version of a document to base an

implementation.

o Guidelines for implementation of standards' defects will be as

per the resolution of such defects by the appropriate ISO

standards committee.

5.9.1 Specific ASE Requirements for ACSE. Presentation, and

Session

The following lists for each ASE the corresponding NBS sig's

requirements of and restrictions on ACSE, Presentation, and

Session.

All listed requirements and restrictions shall be included in an

NBS conformant system and shall be implemented in accordance with

these NBS Implementors' agreements.

The acronym OIV is used for "OBJECT IDENTIFIER VALUE" in the

following lists. Its structure is explained in appendix B.

5 . 9 . 1

1 FTAM

5 , 9 . 1 . 1 ,Phase 2

ACSE Requirements:

all

Application Contexts:

o ISO FTAM - implies the use of the ACSE and the FTAM

ASE.

OIV ={13 9999 1 ac (0) iso-ftam (100) }

Abstract Syntaxes:

o ISO 8650-ACSE1

OIV ={13 9999 1 as (1) iso-8650-acsel (0) }

5-10
Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 ts (2) be-asnl (0) }

Presentation Requirements:

Presentation Functional Units:

o kernel

Presentation Contexts:

o At least 4 Presentation Contexts must be supported.

Abstract Syntaxes:

o FTAM-FADU

OIV ={13 9999 1 as (1) ftam-fadu (101) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

o FTAM unstructured binary abstract syntax

OIV ={13 9999 1 as (1) ftam-ubas (102) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

o FTAM unstructured text abstract syntax

OIV ={13 9999 1 as (1) ftam-utas (103) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

. o NBS file directory entry abstract syntax

OIV = { 13 9999 1 as (1) nbs-fdeas (104) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

o FTAM- PCI (including ISO 8571-FTAM and ISO 8571-FADU)

OIV ={13 9999 1 as (1) ftam-pci (105) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

o NBS -AS 1 OIV = { 1 3 9999 1 as (1) nbs-asl (106) }

5-11
( 0 ) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl

o NBS-AS2

OIV = { 1 3 9999 1 as (1) nbs-as2 (107) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV = {1 3 9999 1 ts (2) be-asnl (0) }

Session Requirements:

Session Functional Units:

o kernel

o duplex

Version Number: 1

Maximum size of user data field: 512

Session Options:

Session Functional Units:

o resynchronize

only a Resynchronize Type value of "abandon"

Version Number: 1

5.9. 1 .2 MHS

5. 9 .1.2,1 Phase 1

Session Requirements:

Session Functional Units:

o kernel

o half-duplex

o exceptions

o activity management

o minor synchronize

Version Number: 1

Maximum size of user data field: 512

Session Notes

o Restricted use is made by the RTS of the session

services implied by the functional units selected.

Specifically,

5-12
. No use is made of S -TOKEN-GIVE , and

. S -PLEASE -TOKENS only asks for the data token.

o In the S-CONNECT SPDU, the Initial Serial Number should

not be present.

o The format of the Connection Identifier in the SCONNECT SPDU is described in Version 5 of the X. 400-

Series Implementors' Guide.

5 . 9 , 1 , 3 VT

5 . 9 . 1 . 3 .

Phase 1

ACSE Requirements:

all

Application Contexts:

o ?

Abstract Syntaxes:

o ISO 8650-ACSE1

OIV = { 1 3 9999 1 as (1) iso-8650-acsel (0) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

Session Requirements:

Session Functional Units:

o kernel

o duplex

o expedited data

o major synchronize

o resynchronize

only a Resynchronize Type value of "abandon"

o typed data

Version Number: 1

Maximum size of user data field: 512

Presentation Requirements:

Presentation Functional Units:

o kernel

5-13
Presentation Contexts:

o ?

Abstract Syntaxes:

o ? Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

5. 9 .1.3.

Phase 2

ACSE Requirements:

all

Application Contexts:

o ?

Abstract Syntaxes:

o ISO 8650-ACSE1

OIV ={13 9999 1 as (1) iso-8650-acsel (0) }

Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

Session Requirements:

Session Functional Units:

o kernel

o duplex

o expedited data

o half -duplex

o major synchronize

o resynchronize

only a Resynchronize Type value of "abandon"

o typed data

Version Number: 1

Maximum size of user data field: 512

Presentation Requirements:

Presentation Functional Units:

o kernel

Presentation Contexts:

o ?

5-14
X

Abstract Syntaxes:

o ? Associated Transfer Syntax:

o Basic encoding rules for ASN.l

OIV ={13 9999 1 ts (2) be-asnl (0) }

5.10 TEST REQUIREMENTS

T.B.D.

;

5-15
5.11 APPENDIX A: RECOMMENDED PRACTICES

5.11.1 Reflect Parameter Values

The optional "Reflect Parameter Values" parameter in the provider

ABORT SPDU shall be encoded so as to represent the Session

connection state, the incoming event and the first invalid SPDU

field exactly at the moment a protocol error was detected.

The first octet encodes the Session state as a number relative to

0 as detailed in Table 1.

The second octet encodes the incoming event as a number relative

to 0 as detailed in Table 2.

The third octet contains the SI, PGI , or PI Code of any SI field,

PGI unit or PI unit in error.

Note: The remaining 6 octets are undefined herein.

5-16
Table 5A.1 Session States

State rel . # Description

1 0 Idle, no transport connection

IB 1 Wait for T-connect confirm

1C 2 Idle, transport connected

2A 3 Wait for the ACCEPT SPDU

3 4 Wait for the DISCONNECT SPDU

8 5 Wait for the S -CONNECT response

9 6 Wait for the S -RELEASE response

16 7 Wait for the T-DISCONNECT indication

13 8 Data Transfer state

1A 9 Wait for the ABORT ACCEPT SPDU

4A 10 Wait for the MAJOR SYNC ACK SPDU or PREPARE SPDU

4B 11 Wait for the ACTIVITY END ACK SPDU or PREPARE SPDU

5A 12 Wait for the RESYNCHRONIZE ACK SPDU or PREPARE SPDU

5B 13 Wait for the ACTIVITY INTERRUPT SPDU or PREPARE SPDU

5C 14 Wait for the ACTIVITY DISCARD ACK SPDU or PREPARE SPDU

6 15 Wait for the RESYNCHRONIZE SPDU or PREPARE SPDU

10A 16 Wait for the S-SYNC-MAJOR response

10B 17 Wait for the S -ACTIVITY- END response

1 118 Wait for the S -RESYNCHRONIZE response

1 IB 19 Wait for the S -ACTIVITY- INTERRUPT response

11C 20 Wait for the S -ACTIVITY- DISCARD response

15A 21 After' PREPARE, wait for the MAJOR SYNC ACK SPDU or the

ACTIVITY END ACK

15B 22 After' PREPARE, wait for the RESYNCHRONIZE SPDU or the

ACTIVITY DISCARD SPDU

15C 23 After' PREPARE, wait for the RESYNCHRONIZE ACK SPDU, or

the ACTIVITY INTERRUPT ACK SPDU or the ACTIVITY DISCARD

ACK SPDU

18 24 Wait for GIVE TOKENS ACK SPDU

19 25 Wait for a recovery request or SPDU

20 . 26 Wait for a recovery SPDU or request

21 27 Wait for the CAPABILITY DATA ACK SPDU

22 28 Wait for the S- CAPABILITY- DATA response

5-17
Table 5A.2 Incoming Events

Event Rel . # Description

SCONreq 0 S -CONNECT request

SCONrsp+ 1 S -CONNECT accept response

SCONrsp- 2 S-CONNECT reject response

SDTreq 3 S-DATA request

SRELreq 4 S -RELEASE request

SRELrsp+ 5 S -RELEASE accept response

SUABreq 6 S-U-ABORT request

TCONcnf 7 T-CONNECT confirmation

TCONind 8 T- CONNECT indication

TDISind 9 T-DISCONNECT indication

TIM 10 Time out

AA 11 ABORT ACCEPT

AB-nr 12 ABORT - no reuse

AC 13 ACCEPT

CN 14 CONNECT

DN 15 DISCONNECT

DT 16 DATA TRANSFER

FN-nr 17 FINISH - no reuse

RF-nr 18 REFUSE - no reuse

SACTDreq 19 S-ACTIVITY- DISCARD request

SACTDrsp 20 S -ACTIVITY-DISCARD response

SACTEreq 21 S -ACTIVITY- END request

SACTErsp 22 S -ACTIVITY- END response

SACTIreq 23 S -ACTIVITY- INTERRUPT request

SACTIrsp 24 S -ACTIVITY- INTERRUPT response

SACTRreq 25 S- ACTIVITY- RESUME request

SACTSreq 26 S -ACTIVITY- START request

SCDreq 27 S- CAPABILITY- DATA request

SCDrsp 28 S- CAPABILITY-DATA response

SCGreq 29 S- CONTROL-GIVE request

SEXreq 30 S- EXPEDITED -DATA request

SGTreq 31 S-TOKEN-GIVE request

SPTreq 32 S- TOKEN -PLEASE request

SRELrsp- 33 S-RELEASE response reject

SRSYNreq(a) 34 S -RESYNCHRONIZE request abandon

SRSYNreq(r) 35 S- RESYNCHRONIZE request restart

SRSYNreq(s) 36 S- RESYNCHRONIZE request set

SRSYNrsp 37 S -RESYNCHRONIZE response

SSYNMreq 38 S-SYNC-MAJOR request

SSYNMrsp 39 S - SYNC -MAJOR response

SSYNmreq 40 S- SYNC -MINOR request

SSYNmrsp 41 S-SYNC-MINOR response

STDreq 42 S- TYPED -DATA request

SUERreq 43 S-U- EXCEPTION-REPORT request

AB-r 44 ABORT - reuse SPDU

5-18
/

Table 5A.2 continued

Event Rel . # Description

AD 45 ACTIVITY DISCARD SPDU

ADA 46 ACTIVITY DISCARD ACK SPDU

AE 47 ACTIVITY END SPDU

AEA 48 ACTIVITY END ACK SPDU

AI 49 ACTIVITY INTERRUPT SPDU

AIA 50 ACTIVITY INTERRUPT ACK SPDU

AR 51 ACTIVITY RESUME SPDU

AS 52 ACTIVITY START SPDU

CD 53 CAPABILITY DATA SPDU

CDA 54 CAPABILITY DATA ACK SPDU

ED 55 EXCEPTION DATA SPDU

ER 56 EXCEPTION REPORT SPDU

EX 57 EXPEDITED DATA SPDU

FN-r 58 FINISH - reuse SPDU

GT 59 GIVE TOKENS SPDU

GTA 60 GIVE TOKENS ACK SPDU

GTC 61 GIVE TOKENS CONFIRM SPDU

MAA 62 MAJOR SYNC ACK SPDU

MAP 63 MAJOR SYNC POINT SPDU

MIA 64 MAJOR SYNC ACK SPDU

MIP 65 MINOR SYNC POINT SPDU

NF 66 NOT FINISHED SPDU

PR-MAA 67 PREPARE (MAJOR SYNC ACK) SPDU

PR-RA 68 PREPARE (RESYNCHRONIZE ACK) SPDU

PR-RS 69 PREPARE (RESYNCHRONIZE) SPDU

PT 70 PLEASE TOKENS SPDU with Token Item Parameter

RA 71 RESYNCHRONIZE ACK SPDU

RF-r 72 REFUSE - reuse SPDU

RS-a 73 RESYNCHRONIZE - abandon SPDU

RS-r 74 RESYNCHRONIZE - restart SPDU

RS-s. 75 RESYNCHRONIZE - set SPDU

TD 76 TYPED DATA SPDU

;

5-19
5.12 APPENDIX B: OBJECT IDENTIFIER: STRUCTURE AND ALLOCATION

In order to complete a stable version of the NBS OSI Implementation

Agreements, the following objects need to be administered by an ad hoc

registration authority:

Application Context Name

Abstract Syntax Name

Transfer Syntax Name

Document Type Name

Constraint Set Name

Since all objects to be administered by the NBS Workshop Sigs are

identified by the ASN.l type OBJECT IDENTIFIER, the following

structure shall be used:

Using the NameAndNumberForm (::= identifier (NumberForm) ) for an

Obj IdComponent we have:

Obj ectldentif ierValue : := { identifier! (NumberForml

)

identified (NumberForm2)

identifier3 (NumberForm3)

identified (NumberForm4)

identifiers (NumberForm5)

identifier6 (NumberFormS) }
The assignment of identifiers and NumberForms is as follows:

identifier! NumberForml

iso 1

identifier2 NumberForm2

identified-organization 3

identifier3 NumberForm3

issuing-organization 9999

identifier4 NumberForm4

organization- code 1

identifiers NumberForm5

application-context 0

abstract -syntax 1 transfer -syntax 2

document- type 3

constraint-set 4

Note 1: The value of NumberForm3 is selected for use by implementors

of these agreements: it has not been assigned by ISO or by

any official Registration Authority. It does correspond to

an "ad hoc" issuing organization with an ICD of 9999, as

specified by ISO 6523. We intend to use the procedure

designated in D.7 of the Specification of ASN.l, ISO 8824

once the appropriate Registration Authority has been

established. This mechanism is subject to change dependent

upon ISO standards.

Note 2: Specific values for identifier6 and NumberForm6 are chosen

as needed by the editor of the UL sig. A table of the

currently allocated values is given later.

Note 3: The NBS UL SIG will assign values for identif ier5 and

NumberForm5 as required by other sigs.

Note 4: Companies wishing to interoperate may designate themselves

with an organization code other than 1 under

{ iso (1) identified-organization (3) - issuing-organization (9999) } for the purpose of defining

private OBJECT IDENTIFIERS.

5-21
Table 5B.1 TABLE OF ALLOCATED OBJECT IDENTIFIERS

The values of the first 4 NumberForms are constant, so the table below

only specifies which registered-object-values are associated with each

registered-obj ect- type

application-context (ac)

iso-ftam (100)

abstract -syntax (as)

iso-8650-acsel (0)

ftam- fadu (101)

ftam-ubas (102)

ftara-utas (103)

f tam-fdeas (104)

ftara-pci (105)

nbs-asl (106)

nbs-as2 (107)

transfer- syntax (ts)

be-asnl (0)

document- type (dt)

constraint -set (cs)

5-22
6. ISO PIS FILE TRANSFER. ACCESS. & MANAGEMENT

6 . 1 INTRODUCTION

This section defines Implementors' Agreements based on ISO File

Transfer, Access, and Management (FTAM) , as defined in ISO 8571. This

International Standard has four parts. Part 1 of the IS gives general

concepts, Part 2 defines the Virtual Filestore (VFS) , Part 3 defines

the File Service, and Part 4 defines the File Protocol.

FTAM, as described in the IS, depends on ISO definitions of ASN.l (ISO

IS 8824 and 8825), the Presentation Service and Protocol (ISO 8822 and

8823), the Session Service (ISO 8326/CCITT X.215) and Session Protocol

(ISO 8327/CCITT X.225). FTAM Phase 2, defined in this section, also

requires ACSE Services (ISO 8649-2 and ACSE Protocol (ISO 8650-2) . These services and protocols are defined architecturally in the OSI

Reference Model (ISO 7498) . This section presumes that the reader is

familiar with these standards, and possesses technical knowledge

appropriate to implementing or testing them. This section provides

detailed guidance for implementors, and is not an FTAM tutorial.

The general agreements reached with respect to the ISO File Transfer,

Access, and Management Protocol (FTAM) are:

FTAM is defined in phases. The Phase 1 FTAM implementation

specification (stable document) is based on the second ISO draft

proposal, dated April 30, 1985, ^ and the ISO draft proposals 8824 and

8825.

The Phase 2 FTAM specification (this section) is based on the

International Standard (IS). THERE IS NO BACKWARD COMPATIBILITY WITH

NBS FTAM PHASE 1. Backward compatibility is impossible, since Phase 1 uses Session services directly, while Phase 2 uses ACSE and

Presentation services. Furthermore, there are differences in

Filestore, PDU Abstract Syntax, FADU Abstract Syntax, and Transfer

Syntax. There also are differences in the transparency mechanisms and

service class negotiations.

The Clmplementation Information> parameter of F- INITIALIZE FPDU as

defined in ISO 8571-4, 20.3 is used to pass 'user version' information

with respect to different FTAM phases of the NBS Implementors

Agreements or with respect to FTAM profiles of other bodies (see

section 6.13 of this document). It is the goal of these agreements to

use the "user version" mechanism to provide at least one level of

backward compatibility for all future NBS FTAM Phases, facilitating

backward compatibility for future FTAM products, assuming different

new versions of the respective IS's also enable backward

compatibility.

^ Part 1 is dated April 20, 1985; Part 2 dated April 29, 1985; and

Parts 3 and 4 dated April 30, 1985.

6-1
6.2 SCOPE AND FIELD OF APPLICATION

These FTAM Phase 2 Agreements cover transfer of and access to files

between the filestores of two end systems, including the management of

a Virtual Filestore. One end system acts in the Initiator role and

initiates the file transfer/access, the other end system acts in the

Responder role and provides access to the file in the Virtual File

Store. This paper describes agreements for the actions and attributes

of the Virtual Filestore, and the service provided by the file service

provider to file service users, together with the necessary

communications between the Initiator and Responder.

Figure 6.1 Model of file transfer/access

Note: Agreements apply on the double lines of Figure 1.

The mapping between the Virtual Filestore and the Real Filestore

together with the local data management system is not part of

these agreements.

These Agreements define FTAM functions for a minimal functionality

(Conformant Implementations) and for several Implementation Profiles

which are tailored to different classes of user requirements to FTAM.

6 . 3 STATUS

This version of the FTAM implementation agreements was completed

December 18, 1987. No further enhancements will be made to this

version. See the next section, ERRATA.

Note: These agreements were updated from the previous March 1987 DIS

based agreements.

6-2
/

6 . 4 ERRATA

6.5 ASSUMPTIONS

1. FTAM protocol machines must be able to parse and process at a minimum 7K octets of FTAM PCI and FTAM user data (including

grouped FPDUs) as they would be encoded with the ASN.l Basic

Encoding Rules. It is recommended, however, that Presentation

user data not be restricted in size.

2. In order to maximize interoperability, it is important that the

implementations of FTAM service providers do not unnecessarily

restrict the service user's ability to generate arbitrary file

service requests. Otherwise, they may not be able to work with

FTAM Responders whose operation is constrained by their mapping

of the FTAM virtual filestore to their local filestore. For

example, error procedures should only be invoked when an error

actually occurs, not at the point of the specification of options

which might result in a error.

3. Implementations must be able to parse all valid optional

parameters if they are present in the PDU. Only those optional

parameters specified as supported in these agreements are

required to be implemented. If these parameters are not present,

a default value is assigned locally. A responder should not

refuse a request solely because a parameter that is optional in

the FTAM standard, but is supported in these agreements, is not

present

4. Consideration of any standardized service interface is not

covered by these agreements.

5. These agreements define no restrictions for the values used for

the <CommunicationQualityOfService> parameter in <F- INITIALIZE>

6.6 PRESENTATION AGREEMENTS

The following Abstract Syntaxes are recognized in these agreements:

'FTAM FADU'

'FTAM PCI'

'FTAM unstructured text abstract syntax'

'FTAM unstructured binary abstract syntax'

'NBS abstract syntax AS1'

'NBS file directory abstract syntax'

1

6-3
The following Transfer Syntax is supported:

'Basic Encoding of a single ASN.l type'

6.7 (See Appendix A, Part 3)

SERVICE CLASS AGREEMENTS

Implementation agreements have been reached for the following service

classes

o File Transfer

o File Access

o File Management

o File Transfer and Management

o Unconstrained

6,8

FUNCTIONAL UNIT AGREEMENTS

Implementation agreements have been reached for the following

functional units.

o Kernel

o Read

o Write

o File Access

o Limited File Management

o Enhanced File Management

o Grouping

Implementation of the Recovery, Restart Data Transfer, and FADU

Locking functional units is not specified.

6,9

FILE ATTRIBUTE AGREEMENTS

Implementation of the Kernel Group of file attributes is defined. If

the optional Storage Group and Security Group are implemented, aspects

of their implementation are defined. Implementation of the Private

Group is not specified.

Responses to an attribute value request shall always include one of

the following (as specified in ISO 8571-2, clause 9.4):

o An actual file attribute value.

o A value indicating that no value is available, optionally with a diagnostic

6-4
o No value and an error code, optionally with a diagnostic, that

the attribute is not supported.

o For the purposes of interworking according to these agreements

the <ContentsType> attribute is limited to the <DocumentTypeName>

format. The <ConstraintSetName , Abs tractSyntaxName> form is

outside the scope of these agreements, but it should always be

parsed correctly when received, but may result in an error.

Mandatory Group

Only the Kernel Group of attributes is required. A value for file

name, permitted actions, and contents type will always be available.

A minimum range is required for <filename> values as specified in ISO

8571-2. No maximum length or format restrictions apply. A system

that does not support <filename> values with a sequence for more than

one Graphic Strings or extended <filename> characteristics may reject

a request involving such a <filename>. All systems must be able to

interpret a <filename> value with a sequence of one Graphic String.

Requests using such a single component <filename> value with a sequence of one GraphicStrings are responded to using single component

<filename> value. Responses to requests involving <filename> values

having two or more Graphic Strings are not defined here but may be

interpreted via bilateral or other external agreements. Use of

<filename> values with a sequence of more than one Graphic Strings is

discouraged.

Optional Groups

If the optional Security Group of file attributes is implemented, an

actual value must be available for the <AccessControl> attribute.

Implementation of the <Private> Group is not specified.

6.10 DOCUMENT TYPE AGREEMENTS

These document types are defined.

FTAM-1 'ISO FTAM unstructured text'

FTAM-2 'ISO FTAM sequential text'

FTAM- 3 'ISO FTAM unstructured binary'

NBS-6 'NBS FTAM sequential file'

NBS-7 'NBS FTAM random access file'

NBS -8 'NBS FTAM indexed file'

NBS -9 'NBS FTAM file-directory file'

Detailed document type definitions are given in Appendix 6A and in ISO

8571-2, Annex B.

Note: Document types NBS-1 to NBS-5 are not defined in these

6-5
agreements. The numbering starts with NBS-6 because of the original

DIS version of these agreements.

An implementation claiming conformance to these Agreements which also

supports any or all of the document typ.es FTAM-1, FTAM-2, and FTAM-3

as defined in ISO 8571-2, Annex B, must support the combinations of

parameter values as specified in Table 6.1.

Table 6.1 Parameters for FTAM-1, -2, -3

Universal Maximum String

Class Number String Length

Significance

FTAM-1 General String *(27)

IA55 String 2 (22) - 134 or less no significance

FTAM-2 Graphic String ^>^(25) 134 or less^ no significance

FTAM-3 <not applicable> 512 or less no. significance^

Notes

1. The minimum level of support for General String is the IA5 GO

character set and the 8859-1 GO and G1 character sets, and IA5 CO

set

2. The support for IA5 String is the IA5 GO character set and the

IA5 CO set.

3. The minimum level of support for Graphic String is the IA5 GO

character set and the 8859-1 GO and G1 sets.

4. This is the default when the parameter is not specified.

5. The implementation need not support Data Units whose total

character count exceeds 134.

6. As per Table 6.3.

For the use of FTAM-2 only the FADU identities of 'begin', 'end',

'first', and 'next' are required for conformant implementations.

For the document types NBS-6, NBS-7 and NBS-8 parameters are used for

which the agreements apply as specified in Table 6.2.

6-6
Table 6.2 Parameters for NBS-6, NBS-7, NBS-8

Parameter PrimType String-length Length

Length-2

int INTEGER Number of octets

required to represent,

in 2's complement

format, the largest

integer to be passed

bit BIT STRING Number of bits in

string

(non-varying)

ia5 IA5 String Max number of

characters in string

graphic Graphic

String

Max number of

characters in string

general General

String

Max number of

characters in string

octet OCTET STRING Max numbers of octets

in string

privateclass-number

Floating

Point

Number

The minimum

number of bits

required to be

maintained in

the mantissa for

relative

precision

Number of bits

required to

represent the

largest unbiased

integer exponent

in 2's

complement

univertime

UTCTime <not applicable>

gen-time Generalized

Time

<not applicable>

boolean BOOLEAN <not applicable>

null NULL <not applicable>

6-7
Note: The string length parameter specifies the actual number of

characters from the referenced character set. It does not include any

escape sequences or overhead from the encoding.

The primitive data types and minimal size ranges that an

implementation must accept for storage are given in Table 6.3.

Table 6.3 FTAM primitive data types

PRIMITIVE DATA TYPE MINIMUM RANGE ('OCTETS')

ASN.l INTEGER 1 - 2

ASN.l BIT STRING 0 - 1 ASN.l IA5String 0 - 134

ASN.l GeneralString 0 - 134

ASN.l Graphicstring 0 - 134

ASN.l OCTET STRING 0 - 512

ASN.l BOOLEAN

ASN.l NULL

ASN.l GeneralizedTime

ASN.l UniversalTime

NBS-AS1 FloatingPointNumber mantissa 1-23 bits

exponent 0-8 bits

Note

1. The primitive data types and their maximum ranges for a specific

file as described by the parameters above are maintained in the

contents type file attribute. The contents type file attribute

value is established at the file's creation and cannot be changed

via FTAM for the life of the file. This implies that the data

element types and ranges and data unit formats are fixed for all

accessors of that file as long as the file exists.

Note

2. The syntax for floating point numbers is part of the definition

of NBS abstract syntax AS1 in Annex 6A Part 3. It is derived

from existing standards IEC 559 and IEE 754.

6-8
6 . 10.1 Character Sets

Implementation of a character set in FTAM is understood as:

o a transfer syntax is defined for the character set

o document types are defined using the character set in

their abstract syntactic definition

o documents of those types are stored in the Virtual File

Store as defined in the character set specification.

They are written into the VFS and read from the VFS as

defined by the abstract syntax and the transfer syntax

for the document type. It is not in the scope of FTAM

Agreements to specify the local representation of those

documents in the Real File, nor to specify rendition of

graphic characters or control characters on character

imaging devices. These renditions are possible

agreements between applications using FTAM for their

communication.

The character sets IA5 and ISO 8859-1 shall always be

implemented.

6.10.1,1 IA5 Character Set

The International Reference Version (IRV) of IA5 is

available for use when there is no requirement to use a national or an application-oriented version. In information

interchange, the IRV is assumed unless a particular

agreement exists between sender and receiver of the data.

The graphic characters allocated to the IRV are as specified

in Table 6.4.

6-9
Table 6.4. IRV Graphic Character Allocations

Graphic Name Coded Representation

# Number sign 2/3

$ Currency sign 2/4

@ Commercial at 4/0

[ Left square bracket 5/11

\ Reverse solidus 5/12

] Right square bracket 5/13

A Circumflex accent 5/14

f Grave accent 6/0

{ Left curly bracket 7/11

1 Vertical line 7/12

} Right curly bracket 7/13

Tilde, overline 7/14

It should be noted that no substitution is allowed when using the IRV

and that the facility of combined vertical and horizontal movements of

the active position does not apply to any format effectors.

It is permitted to use composite graphic characters and there is no

limit to their number. Because of this freedom, their processing and

imaging may cause difficulties at the receiving end. Therefore

agreement between sender and receiver of the data is recommended if

composite characters are used.

Note: Attention is drawn to the fact that different national character

sets exist.

(See ISO 646 or CCITT Recommendation T.50)

6-10
6.10.1.2 8859-1 Character Set

The Latin Alphabet No.l (ISO 8859-1) is used to specify the

printable characters of GO and G1 , CO control characters

and their associated rules are taken from the IA5

definition.

6.10.2 Document Type Negotiation Rules

6,10.2.1 Connection Establishment

In Connection Establishment the CContentsTypeLis t> parameter

is used only to establish presentation contexts. Both the

<DocumentTypeName> form and the <AbstractSyntaxName> form

are supported. 6.10.2.2

File Creation

An F-CREATE Request FPDU must contain a <DocumentTypeName>

value in its <InitialAttributes> parameter. This document

type name is either a value from the set of base document

type names as negotiated upon connection establishment or a document type name, for which an appropriate presentation

context was established.

If the specified document type requires parameterization,

then these parameters must be supplied, otherwise the FCREATE Request may be rejected.

Notes

1. It is understood that <permitted actions> subfield of Cinitial attributes> parameter will

always be used at F-CREATE Request. The value may

be changed by the Responder.

2. If the <DocumentTypeName> used requires DU syntax

parameters and one of the parameters specifies

<FloatingPointNumber> as a primitive data type,

the request may be rejected, in case the optional

<FloatingPointNumber> type is not supported by the

Responder

6,10.2.3

File Opening

The <DocumentTypeName> form (with appropriate parameters as

specified in 8871-2, clause 12.3) shall always be used when

proposing a <ContentsType>; as an alternative the

' ContentsTypeUnknown' value may be used in the F-OPEN

Request. An F-OPEN Response shall use the

6-11
<DocumentTypeName> option (with appropriate parameters) in

the <ContentsType> field.

This allows the receiving entity to use the

<DocumentTypeName> attributed to the file instead of

receiving a CConstraint Set Name> and <Abs tract Syntax Name>

pair, which does not reflect the file information contained

in the FTAM and NBS document types.

Note

1 . An F-OPEN response without a <DocumentTypeName> (but

carrying the CConstraint Set Name> and CAbstract Syntax

Name> form) may cause the initiator to issue an F-CLOSE

request

2. If the <DocumentTypeName> used requires DU syntax

parameters and one of the parameters specifies

<FloatingPointNumber> as a primitive data type, the

request may be rejected, in case the optional

<FloatingPointNumber> type is not supported by the

Responder

6.10.3 Relationship Between DUs . DEs and Document Types

"Abstract Syntax" is used to refer to the syntactic information

which is architecturally passed between the Application and

Presentation Layers. The Abstract Syntax defines Data Element

(DE) types which are not necessarily ASN.l primitive types. A

Data Element (DE) is the smallest piece of data whose identity is

necessarily preserved by the Presentation Service. Data types

may be made up of other data types. Data Elements are not

defined in terms of other Data Elements.

A Data Unit (DU) is a sequence of one or more data elements.

Architecturally, entire, single DEs are passed into and out of

the application process. In a real implementation, DUs may be

passed.

To maintain DU boundaries during transfer, file structuring

information must be passed (IS08571-FADU definition in IS08571-2,

clause 7.5), A data element is referred to as a File-ContentsData-Element in an IS08571-FADU definition.

Document types refer to aspects of local processing and storage.

They describe:

o structural relationship between DUs,

o structure of DUs, called DU syntax, and

o data element types found in the file.

Because document types pertain to local processing and storage,

6-12
the DU syntax makes assertions about the syntax and the size of

DUs (records) in storage. Parameters on the document types

provide this information about the syntax and size of the DUs.

6.11

F- CANCEL ACTION

When an F-CANCEL is sent or received, the following occurs:

o no more data is sent,

o <checkPointNumbers> are removed, and

6.12 o state of the file is implementation dependent.

IMPLEMENTATION INFORMATION AGREEMENTS

o The dmplementation Information> parameter of F-INITIALIZE FPDUs

is supported

o It may be used to pass user version information as a series of

values, separated by (;).

o The following will indicate the NBS Phase 2 Agreements: NBSPhase2

Note: The list of possible values may be enlarged for future FTAM

phases or FTAM profiles of other bodies.

o This parameter is for information only: it is not used for

negotiation

The establishment of an FTAM regime should not be rejected only

because of an unknown dmplementation Information> value.

6,13

DIAGNOSTIC AGREEMENTS

1. The <diagnostic> parameter is supported; a value in the Response

PDU is needed only, when the Action Result or State Result is not

zero. (The nature of these agreements is to provide <diagnostic>

information when any result parameter is not <success>.)

2. General catch-all diagnostic action is discouraged.

3. The <furtherDetails> subfield is supported. It will be encoded

as Graphicstring, but is restricted to IA5 (IRV, graphic

characters) and IS08859-1 only.

4. Use of F-P-ABORT for other than protocol errors and catastrophic

situations is discouraged.

5. When returning an error status in a file management related

6-13
diagnostic (i.e., F-READ-ATTRIBUTEresponse or FCHANGE-ATTRIBUTEresponse) , identify the erroneous attribute by

using the first two characters of <further-details> to hold a

2-digit number (encoded in IA5String) from the

F-READ-ATTRIBUTErequest attributes abstract syntax definition

(IS08571-4, clause 20.3).

00 Filename

01 Permitted Actions

02 Contents Type

03 Storage Account

04 Date and Time of Creation

05 Date and Time of Last Modification

06 Date and Time of Last Read Access

07 Date and Time of Last Attribute Modification

08 Identity of Creator

09 Identity of Last Modifier

10 Identity of Last Reader

11 Identity of Last Attribute Modifier

12 File Availability

13 File Size

14 Future Filesize

15 Access Control

16 Legal Qualifications

17 Private Use

The set of File Management <diagnostics>, found in IS08571-3

Annex A, must be supported.

6. In the case where a specific parameter can in no way be

accommodated then the request fails and a <diagnostic> indicating

one such parameter should be returned by the responder. In the

case where a negotiable parameter cannot be accommodated with

exactly the value requested but is negotiated to a different

value (as defined in the standard) then the request formally

succeeds but informative <diagnostics> indicating those

parameters negotiated should be returned.

6.14 CONCURRENCY

The Concurrency control> used by default on actions requested by an

F-SELECT Indication or F-CREATE indication service are:

Shared for read and read attribute

Exclusive for all other actions

The default for actions not requested is specified as 'not required'

as per IS08571-3.

Note: A local implementation may choose to be more restrictive in

order to assure file consistency for concurrent accessors.

6-14
FADU locking is not required.

6.15 REQUESTED ACCESS

The <RequestedAccess> parameter on <F-SELECT> or <F-CREATE> is used to

specify the actions which the initiator may perform during the file

selection. The value of the <RequestedAccess> parameter is compared

by the responder to the <AccessControl> and <PermittedActions> file

attributes and concurrency controls (including those requested by the

initiator) currently in place on the file. If the value of the

<RequestedAccess> parameter is not consistent with either

<AccessControl>, <PermittedActions>, or concurrency controls in place,

then the <F-SELECT> or <F-CREATE> must be rejected.

<RequestedAccess> is consistent with <AccessControl> if, for each

action requested, that action either requires no password, or the

required password has been specified on the <F-SELECT> or <F-CREATE>

request

<RequestedAccess> is consistent with <PermittedActions> if, for each

action requested, that action is allowed by the <PermittedActions>

file attribute.

<Reques tedAccess> is consistent with <ConcurrencyControl> requested on

the <F-SELECT> or <F-CREATE> if, for each action requested, that

action has not been specified as <not required> or <no access> in the

<ConcurrencyControl> parameter.

<RequestedAccess> is consistent with concurrency controls in place on

the file if for each action requested no other accessor of the file

has set the concurrency control for that action to either <exclusive>

or <no access>.

6.16 SECURITY

6.16.1 Optional Password Support

Users may provide values for <InitiatorIdentity> and

<FilestorePassword>. Password support in FTAM is not required.

If this information is provided, it will be sent to the Responder

on the F- INITIALIZE.

The syntax of <InitiatorIdentity> and <FilestorePassword> is

system-dependent. <InitiatorIdentity> and <Files torePassword>

will represent "account" information on the local system, which

may be different from the <account> parameter.

6-15
6.16.2 Access Passwords

Users may provide <accessPasswords>. If the information is

provided, the passwords will be sent to the Responder in the

<AccessPasswords> parameter.

6.16.3 Implementation Responsibilities

It is the responsibility of each local system to provide security

for its own real filestore. Encryption of passwords will not be

done by FTAM.

A user of the file service must be known by the Responder.

"Known" is defined by the local Filestore, and is dependent on

the level of security provided by the local Filestore.

6,17 REQUIREMENT FOR CONFORMANT IMPLEMENTATIONS

This section gives the criteria to be satisfied by every

implementation of FTAM that conforms to these agreements.

Conformance to these agreements is stated in terms of the different

roles occupied by FTAM implementations. The interoperability of

certain configurations of these roles motivates this approach.

Interoperable configurations of these roles are given in Section

6.17.1.

The only function provided by every conformant implementation is the

transfer of unstructured binary files in their entirety. It must be

recognized that such simple transfer, while commonly understood and

generally important, will not support all applications of FTAM.

Section 6.18 defines implementation profiles of FTAM services and

protocol that can provide other specific functions. Those other

functions exploit the access and management capabilities of FTAM. The

unconstrained service class (with appropriately chosen functional

units) can be used to provide the functions of any of the

implementation profiles. Users of FTAM must consider carefully what

functions they require. They must examine all the implementation

profiles and select according to their needs.

6.17.1 Interoperable Configurations

Any implementation conforming to this specification must be able

to act in at least one of the following role combinations:

1. initiator and receiver,

2. initiator and sender,

6-16
3.

/

responder and sender,

4. responder and receiver.

Minimal implementations of combination 1 will interoperate with

minimal implementations of combination 3. Minimal

implementations of combination 2 will interoperate with minimal

implementations of combination 4.

Any implementations of roles 1 and 3 will be able to interoperate

at the intersection of their capabilities (which will be at least

the minimal capabilities described in Sections 6.17.3 to 6.17.8).

Any implementations of roles 2 and 4 will be able to interoperate

at the intersection of their capabilities (which will be at least

the minimal capabilities described in Sections 6.17.3 to 6.17.8).

These role combinations and this interoperability are shown in

table 6.5 below.

Table 6.5 Interoperable configurations

Initiator Responder

sender receiver sender receiver

Initiator

sender X

receiver X

Responder

sender X

receiver X

6.17.2 Relationship to ISO 8571- -The FTAM Standard

Any implementation in conformance to ISO 8571 (as defined in ISO

8571-4, clause 22 (Conformance)), in addition to the

implementation of the minimal protocols and roles enumerated in

Sections 6.17.3 to 6.17.8, is considered to be in conformance

with these agreements. Any implementation violating any of the

conformance statements in ISO 8571-4 is considered to be in

violation of these agreements.

6-17
6.17.3 Requirements for Document Type Support

The document type FTAM-3 shall be supported for purposes of

transfer and storage. The details regarding support for FTAM-3

in the FTAM dialogue are given in Sections 6.10.

Support of document types other than FTAM-3 is not required for

conformant implementations. Support for document types described

in these agreements also entails support for:

o the semantics given in their description and further

qualified in 6.10

o the preferred transfer syntax "Basic Encoding of a

single ASN.l type"

6.17.4 Initiators

Every implementation of an FTAM initiator shall support:

o the kernel protocol and its mandatory parameters with

minimum ranges [Minimum required ranges are specified

in Section 6.17.8.],

o the grouping protocol and the threshold parameter with

a value of at least 2 for use in the file transfer

class

,

o at least one of the read or write protocols [Specific

conformance for reading and writing is defined in

Sections 6.17.6 and 6.17.7.],

and support the applicable procedures defined in ISO 8571-4

clauses 8.1 (FTAM regime establishment), 8.2 (FTAM regime

termination), 8.3 (File selection), 8.4 (File deselection), 8.9

(File open), 8.10 (File close), 8.11 (Begin group), 8.12 (End

group) , and 10 (File general actions) . To support the above

protocols and procedures the implementation shall always support

the kernel functional unit and additionally shall be able to:

o request the grouping and at least one of the read or

write functional units,

o request the file transfer class with the <service

class> parameter,

o request the document type FTAM-3 using the <document

type name> form of the Ccontents type> parameter,

o request the <FTAM quality of service> parameter with

value 0 and accept in all cases the returned value 0,

6-18
and

o request a Communication quality of service> consistent

with the transport definition in these agreements

as part of the filestore initialization procedures in ISO 8571-4

clause 8.1, FTAM regime establishment.

Initiators must be able to operate under all circumstances if the

above minimum values are successfully negotiated and returned on

an F-INITIALIZEresponse PDU. Initiators must be able to operate

with any downward negotiation of requested parameter values as

described in the standard.

Should the supporting services break down, such that FTAM

communication is impossible, the FTAM protocol machine shall

notify the user with an F-P-ABORT indication and <diagnostic>

value with identifier 1011, as well as any known <further

details>.

Note: Interworking may not be possible between Initiators not

supporting attributes of the Storage Group and Security Group,

and Responders requiring these attributes to be used.

6.17.5 Responders

Every implementation of an FTAM responder shall support:

o the kernel protocol and its mandatory parameters with

minimum ranges [Minimum required ranges are specified

in Section 6.17.8.],

o the grouping protocol and the threshold parameter with

a value of at least 2 for use in the file transfer

class

,

o at least one of the read or write protocols [Specific

conformance for reading and writing is defined in

Sections 6.17.6 and 6.17.7],

and support the applicable procedures, defined in ISO 8571-4

clauses 9.1 (FTAM regime establishment), 9.2 (FTAM regime

termination), 9.3 (File selection), 9.4 (File deselection), 9.9

(File open), 9.10 (File close), 9.11 (Begin group), 9.12 (End

group) , and 10 (File general actions) . To support the above

protocols and procedures the implementation shall always support

the kernel functional unit and additionally shall be able to:

o accept requests for the grouping and at least one of

the read or write functional units,

6-19
o accept requests for the file transfer class with the

<service class> parameter,

o accept the document type FTAM- 3 using the <document

type name> form of the Ccontents type> parameter, and

o accept requests for an <FTAM quality of service>

parameter with any value but may respond with the value

0 , and

o accept requests for a Communication quality of

service> consistent with the transport definition in

these agreements

as part of the filestore initialization procedures in ISO 8571-4

clause 9.1, FTAM regime establishment.

Responders must be able to operate under all circumstances if the

above minimum values are requested on an F-INITIALIZErequest PDU.

Responders must not negotiate upward in the sense described in

the standard.

Responders must complete each action requested and supported in a manner consistent with its description in ISO 8571-2 clauses 10

(Actions on complete files) and 11 (Actions for file access) , and

must interpret each supported attribute in a manner consistent

with its definition in ISO 8571-2 clause 12 (File attributes).

Under circumstances where actions cannot be carried out either as

requested or consistently with ISO 8571-2 clause 10 (Actions on

complete files) and 12 (Actions for file access) , the responder

must return at least one diagnostic indicating:

o if the failure was due to either a protocol or

filestore failure, and then:

precisely which action failed,

at least one of the parameters that could not be

accommodated with the diagnostic type indicating

at least the degree of failure, as given by the

action and state result parameter, or

o that the failure was due to unforeseen system shutdown.

Should the supporting services break down, such that FTAM

communication is impossible, the FTAM protocol machine shall

notify the user with an <F-P-AB0RT indication> and <diagnostic>

with identifier 1011, as well as inform the user of any known

<further details>.

6-20
6.17.6 Senders

Every implementation of an FTAM sender shall support the read

functional unit as responder or the write functional unit as

initiator, and support the applicable procedures defined in ISO

8571-4 clauses 11 (State of the bulk data transfer activity), 12

(Bulk data transfer protocol data units), 15 (Bulk data transfer

sending entity actions), 17.1 (Discarding), and 17.2 (Cancel).

To support those procedures the implementation shall be able to

send files of the document type FTAM- 3 and shall be able to send

them as user data in PPDUs in blocks of up to 7168 octets.

6.17,6.1 Initiator Senders

Every implementation of an FTAM sender which is also an FTAM

initiator shall support:

o the write functional unit and protocol, and

o for the document type FTAM- 3 the following bulk

data transfer specification parameters:

FADU operation replace

FADU identity first

and support the applicable procedures, defined in ISO 8571-4

clause 13 (Bulk data transfer initiating entity actions)

6.17.6,2 Responder Senders

Every implementation of an FTAM sender which is also an FTAM

responder shall support:

o the read functional unit and protocol, and

o for the document type FTAM- 3 the following bulk

data transfer specification parameters:

FADU identity first

Access context UA

and support the applicable procedures, defined in ISO 8571-4

clause 14 (Bulk data transfer responding entity actions)

6-21
6.17.7 Receivers

Every implementation of an FTAM receiver shall support the read

functional unit as initiator or the write functional unit as

responder, and support the applicable procedures, defined in ISO

8571-4 clause 11 (State of the bulk data transfer activity), 12

(Bulk data transfer protocol data units) , 16 (Bulk data transfer

receiving entity actions), 17.1 (Discarding), and 17.2 (Cancel).

To support those procedures the implementation shall be able to

receive files of the document type FTAM- 3 and shall be able to

receive them as user data in PPDUs in blocks of at least 7168

octets

6.17.7.1 Initiator Receivers

Every implementation of an FTAM receiver which is also an

FTAM initiator shall support:

o the read functional unit and protocol, and

o for the document type FTAM- 3 the following bulk

data transfer specification parameters:

FADU identity first

Access context UA

and support the applicable procedures, defined in ISO 8571-4

clause 13 (Bulk data transfer initiating entity actions).

6.17.7.2 Responder Receivers

Every implementation of an FTAM receiver which is also an

FTAM responder shall support:

o the write functional unit and protocol, and

o for the document type FTAM- 3 the following bulk

data transfer specification parameters:

FADU operation replace

FADU identity first

and support the applicable procedures, defined in ISO 8571-4

clause 14 (Bulk data transfer responding entity actions)

6-22
6 . 17.8

/

Minimum Ranges

Any implementation of any conformant FTAM configuration shall be

able to receive and meaningfully process all mandatory parameters

for all functional units supported as- well as the diagnostic

parameter within at least the minimum ranges of values given in

Table 6.6. A conforming implementation may support a wider range

of values for any parameter.

1

6-23
Table 6.6 Required minimal parameter support

Parameter Minimum Range

diagnostic Values as specified in ISO 8571-3 Annex A

(Diagnostic parameter values) Tables 44,

45 and 46 which correspond directly to

mandatory parameters.

action result

state result

All values.

All values.

F_INITIALIZE

functional units^ "read" (for initiator/receivers and

responder/senders) and grouping

or

0 presentation context management4- all others

"write" (for initiator/senders and

responder/receivers) and grouping

"Not required."

As specified in Sections 6.17.4 and

6.17.5 above.

F_S ELECT

attributes Only filename is used with a minimum

supportable length of 8 characters. Any

other attribute supported for other

services must have minimum supported

lengths as in ISO 8571-2 clause 15

(Minimum attribute ranges) Table 2.

requested access "read" for initiator receivers

"read" for responder senders

"replace" for initiator senders

"replace" for responder receivers

F_OPEN

processing mode

j

j

"read" for initiator receivers

"read" for responder senders

"replace" for initiator senders

"replace" for responder receivers

contents type "FTAM-3"

(Continued on next page.)

6-24
Table 6.6 Required minimal parameter support, continued

Parameter Minimum Range

F READ

FADU identity "first"

access context "UA"

F_WRITE

FADU operation "read" for initiator receivers

"read" for responder senders

"replace" for initiator senders

"replace" for responder receivers

FADU identity "first"

F_BEGIN_GROUP

threshold-^ For file transfer (a minimal required

function) 2

Notes

The parameters, functional units, and presentation context

management are not ordered, so "minimum value" cannot be

formally defined. The above values are those required for

conformance to these agreements but no value conformant to

ISO 8571 for use in other applications is regarded to be in

violation of these agreements.

2. Other functional units (and service classes) for defined

implementations may also be valid provided that they are

implemented in accordance with these agreements,

specifically section 6.17.8.

Every implementation must support the threshold value 2 to

provide the basic required function of file transfer; any

other value in other applications is acceptable.

For any other supported parameters, minimum ranges are taken from

the minimum ranges for the attribute corresponding to each as in

ISO 8571-2 Table 2.

6-25
6.18 IMPLEMENTATION PROFILES

This section defines implementation profiles for the specific

functions of:

o File Transfer

o File Access

o File Management.

Those definitions are expressed in terms of:

o Document Types

o Attributes

o Service Classes (both service elements and their

parameters)

This by no means defines all possible implementation profiles.

The following implementation profiles are defined:

T1 : Simple File Transfer

T2 : Positional File Transfer

T3 : Full File Transfer

Al : Simple File Access

A2 : Full File Access

Ml : Management

Implementation agreements have been reached for the following service

classes. Note that any given implementation may support more than one

service class.

o File Transfer

o File Access

o File Management

o Unconstrained

o File Transfer and Management

Support of an implementation profile requires adherence to: 1.

corresponding definition in 8571-3 clause 8 and any related

procedures in 8571-4 clause 8-17, 2. requirements given in Sections

6.5-6.18 of these agreements , and 3. requirements for parameter and

attribute support as defined in Section 6.17.8.

6.18,1 General Requirements for the Defined Implementation Profiles

o Implementations will be able to act either as initiator or

responder or both.

o Implementations must support diagnostics as described in

Section 6.13 of these agreements.

6-26
o Implementations that support the file access service class

will support access to sequential files. Support of

sequential files entails hierarchy of depth and arc length

1. Other hierarchy depth and arc lengths are not precluded

by these agreements.

6.18.2 Use of Lower Laver Services

o Support for the Presentation Context Management

functional unit is not required.

o Implementations will support the Session, Presentation

and ACSE requirements as stated in Section 5.

Note: Implementation of the Session Resynchronize functional

unit is highly recommended, since the F-CANCEL service may be

less effective when mapped to S-DATA.

6.18.3 Document Type Requirements for the Defined Implementation

Profiles

Implementations conformant to implementation profiles defined in Table

6.7 will support the following document types with the caveats and

procedures given. Those document types are defined in Appendix 6A and

section 6.10 of these agreements, and in ISO 8571-2.

o FTAM-1

o FTAM-2

o FTAM-3

o NBS-6

o NBS-7

Note: Support of this document type entails the naming of

FADUs by their position in preorder traversal.

Caveat: Other methods of naming FADUs depend on the system,

application, and specific file, and as such are not

described here.

o NBS-8

o NBS-9

Support for any document type requires the ability to transfer and store

the abstract syntax given in its definition. These agreements do not

specify techniques or formats for storage.

; Caveat: Specific abstract syntaxes for the parameterized document types

6-27
NBS-6,7,8 are not specified in these agreements.

Any document type supported must be identifiable by its document type

name as given in IS08571-1 and in Appendix 6A of these agreements and,

where defined, the parameterization scheme given in Section 6.10 of these

agreements

For conformance to NBS-9 a Responder is only required to return the

filename attribute, subject to local security and access control. All

other requested attributes need not be returned.

Systems supporting the NBS-9 document type shall make available an NBS-9

document called "DIRLIS". This document can be used to obtain a listing

of files and their associated attributes from a remote filestore.

File security issues related to NBS-9 are subject to the security

agreements outlined in section 6.16.

6.18.4 Parameters for the Defined Implementation Profiles

o Use of <shared ASE> parameter and <charging> parameter

is not defined within the scope of these agreements.

o Use of Application context name> parameter is not

defined within the scope of these agreements. This

parameter does not prohibit the establishment of an

FTAM association.

o Implementations will support the <contents type list>

parameter on the F- INITIALIZE service element. The

initiating service must supply a value for this

parameter

o Implementations will support the <diagnostic> parameter

as stated in Section 6.13 of these agreements.

o Implementations will support <Identity of Initiator>

Parameter on the F- INITIALIZE Service Element. If the

initiating service user supplies a value for this

parameter, it will be sent on the request PDU and the

virtual filestore will process the parameter. Use must

be consistent with Section 6.16 of these agreements.

o Implementations are not precluded from using other

parameters for security and/or accounting. Responders

must state the semantics applying to <account> and

<charging> parameters. The Responder's minimum

implementation is to accept but ignore the Account and

to return a <charging> value of zero.

6-28
6.18.5 Parameter Ranges for the Defined Implementation Profiles

Parameter ranges for implementations profiles are as stated for

primitive data types in Section 6.10 of these agreements.

6.18.6 File Attribute Support for Implementations

Implementations of the implementation profiles will support file

attributes in the following ways.

o If an attribute is "supported" it implies a value will

be returned other than the value "no value available"

and the value will follow the rules as stated in these

agreements and in IS08571-2.

o If an attribute is "optionally supported" a value of

"no value available" may be returned.

o If an attribute group is "not supported" then no value

will be returned for any of its attributes.

Kernel Group supported

1. Filename

2. Permitted Actions

3 . Contents Type

supported

supported

supported

Storage Group optionally supported

1. Storage Account

2. Date and Time of Creation

3. Date and Time of Last Modification

4. Date and Time of Last Read Access

5. Date and Time of Last Attribute Modification

6 . Identity of Creator

7. Identity of Last Modifier

8. Identity of Last Reader

9. Identity of Last Attribute Modifier

10. File Availability

11. Filesize

12. Future Filesize

optionally

optionally

optionally

optionally

optionally

optionally

optionally

optionally

optionally

supported

supported

optionally

supported

supported

supported

supported

supported

supported

supported

supported

supported

supported

Security Group optionally supported

1. Access Control

2. Legal Qualifications

supported

optionally supported

Private Group not supported

6-29
Table 6.7 Implementation profile support requirements

Service Class

Functional Unit T M A T&M UNCST

Kernel T1,T2,T3 Ml A1,A2

Read (See note 3.) T1 ,T2,T3 A1,A2

Write (See note 3.) T1 ,T2,T3 Al ,A2

Limited File Mgmnt. SeeNote 6 Ml SeeNote 6 See See

Enhanced File Mgmnt. Ml

Grouping

File Access

T1.T2.T3 Ml

Al ,A2

Document Tvnes

FTAM

T1,T2,T3 Al ,A2

FTAM-2 T2,T3 Al ,A2

FTAM-3 T1 ,T2,T3 Al ,A2 Note Note

NBS-6 [T2 ] ,T3 [Al] ,A2 4 5

NBS-7 [T2 ] ,T3 [Al] ,A2

NBS-8 T3 A2

NBS-9 HCM H

CO H

H

Notes: to 6.18.3 and Table 6.7

1 . The Management Implementation profile is only to be implemented in

conjunction with one of the Transfer or Access profiles.

2. Profile T2 is subset of T3. Al and T1 are subsets of A2 and T2

,

respectively

3. Profiles T1 , T2 , and T3 require the support of read and/or write

functional units.

4. Support of the <File Transfer and Management service class is

optional. If an implementation is capable of supporting

implementation profile Ml and one of the T- implementation profiles,

the Initiator may choose to request the <File Transfer and Management

service class. Any implementation so doing must be prepared for the

possibility of rejection of the request by the responder.

6-30
5. The support of the <uncons trained> service class is optional. There

are no constraints on this service class beyond those of ISO 8571.

6. Limited File Management is not required for the T- and Aimplementation profiles, but very often it will be a user request to

have limited file management functionality available together with

file transfer and file access functions. So limited file management

may be added as an option to the T- and A- implementation profiles.

7. [] in table 6.7 specifies that the document type is 'optional' for the

respective Implementation profile.

6,19 PROVISION 6.19.1 OF SPECIFIC FUNCTION

Implementation Profile T1 : Simple File Transfer

Implementation profile T1 provides the function of transferring

entire files at the external file service level for files with an

unstructured constraint set. This includes support of the

document types

o FTAM-1 ISO FTAM unstructured text

o FTAM- 3 ISO FTAM unstructured binary

o NBS-9 NBS file directory file (optional)

This implementation profile supports file transfer and not file

access, that is, the ability to:

o read a complete file

and/or

o write (replace, extend) to a file.

6.19.2

Implementation Profile T2 : Positional File Transfer

Implementation profile T2 provides the function of transferring

files at the external file service level for files with an

unstructured or flat constraint set. This includes support of

the document types:

o FTAM-1 ISO FTAM unstructured text

o FTAMISO FTAM sequential text

o FTAMISO FTAM unstructured binary

0 NBS -6 NBS FTAM sequential file (optional)

o NBS -7 NBS FTAM random access file (optional)

o NBS-9 NBS file directory file (optional)

1 This implementation profile supports file transfer and not file

6-31
access, that is, the ability to:

o read a complete file or a single FADU which is

identified by position

and/or

o write (replace, extend, insert depending on constraint

set and document type) to a file or an FADU.

This implementation profile is upwardly compatible to T1 for the

transfer of unstructured files.

6,19.3 Implementation Profile T3: Full File Transfer

Implementation profile T3 provides the function of transferring

files at the external file service level for files with an

unstructured, flat or general hierarchical constraint set. This

includes support of the document types:

o FTAM-1

o FTAM-2

o FTAM-3

o NBS-6

o NBS-7

o NBS-8

o NBS-9

ISO FTAM unstructured text

ISO FTAM sequential text

ISO FTAM unstructured binary

NBS FTAM sequential file

NBS FTAM random access file

NBS FTAM indexed file

NBS file directory file (optional)

This implementation profile supports file transfer and not file

access, that is, the ability to:

o read a complete file or a single FADU which is

identified by key or by position

and/or

o write (replace, extend, insert depending on constraint

set and document type) to a file or an FADU.

This implementation profile is upwardly compatible to T1 for the

transfer of unstructured files.

6.19.4 Implementation Profile Al : Simple File Access

Implementation profile Al provides the function of transfer of

and access to files with unstructured or flat constraint sets at

the external file service level. This includes support of the

document types:

6-32
o

o

o

o

o

FTAM-1 ISO FTAM unstructured text

FTAM-2 ISO FTAM sequential text

FTAM- 3 ISO FTAM unstructured binary

NBS-6 NBS FTAM sequential file (optional)

NBS-7 NBS FTAM random access file (optional)

This implementation profile supports file transfer and file

access, that is the ability to:

o read a complete file or FADUs which are identified by

position,

o write (replace, extend, insert depending on constraint

set and document type) to a file or an FADU,

o locate and erase within files.

6.19.5 Implementation Profile A2 : Full File Access

Implementation profile A2 provides the function of transfer of

and access to files with unstructured or flat constraint sets at

the external file service level. This includes support of the

document types:

o FTAM-1 ISO FTAM unstructured text

0 FTAM-2 ISO FTAM sequential text

o FTAMISO FTAM unstructured binary

o NBS-6 NBS FTAM sequential file

o NBS-7 NBS FTAM random access file

0 NBS -8 NBS FTAM indexed file

This implementation profile supports file transfer and file

access, that is, the ability to:

o read from a complete file, or from a series of FADUs

which are identified by key or by position,

o write (replace, extend, insert depending on constraint

set and document type) to a file or an FADU,

o locate and erase within files.

6-33
6.19.6 Implementation Profile Ml: Management

Implementation profile Ml provides the function for an Initiator

to manage the files within the Virtual Filestore, to which access

is provided by the Responder. Management includes the services

of:

o creating a file

o deleting a file

o reading attributes of a file

o changing attributes of a file.

6.20 HARMONIZATION

The implementation profiles for File Transfer, File Access and

Management correspond to the profiles of SPAG (Standards Promotion and

Application Group) in Europe, so that interworking will be possible.

Those profiles are described in the 'Guide to the Use of Standards'

(GUS) ; they will also be the basis for the Functional Standards as

defined by CEN/CENELEC (Comite Europeenne de Normalization)

Table 6.8 Implementation profiles (NBS) and profiles (SPAG)

Implementation Profile SPAG

T1 A/111

T2 A/112

T3 A/113

Al A/122

A2 A/123

Ml A/13

Note: The profiles/functional standards of SPAG/CEN-CLC will

become stable by December 1987.
6.21 FTAM DOCUMENT TYPES

Part 1 Part 2

Part 3

/

APPENDIX A:

Document Types

Constraint Sets

Abstract Syntaxes

1

6-35
Part 1 : Document Types

NBS Sequential file document type

1. Entry Number: NBS -6

2. Information objects

6-36
Table 6.9 Information objects in NBS-6

document type name {iso identified-organization icd (9999)

organ-code (1) document type (5) sequential

(6))

(NBS FTAM sequential file)

abstract syntax names:

a) name for asnamel

b) name for asname2

{iso identified-organization icd (9999)

organ-code (1) abstract-syntax (2) nbs-asl

(0)}

(NBS abstract syntax AS1)

{iso standard 8571 abstract-syntax(2) ftamfadu (2)

}

(FTAM FADU)

transfer syntax names: { j oint- iso-ccitt asnl (1) basic-encoding (1)

) (Basic Encoding of a single ASN.l type)

parameter syntax:

PARAMETERS : := SEQUENCE OF CHOICE {ParameterO, Parameterl, Parameter2)

ParameterO : := universal-class-number-0 [0] INTEGER {univer-time (23)

gen-time (24)

,

boolean ( 1 )

,

null (5) ) Parameterl : := [1] SEQUENCE { universal-class-number-1 INTEGER { int (2),

bit (3),

ia5 (22),

graphic (25),

general ( 27 )

,

octet (4) )

string- length INTEGER } Parameter : := [2] SEQUENCE { private-class-number INTEGER {float (0)},

length- 1 INTEGER,

length- 2 INTEGER )

file model {iso standard 8571 file-model (3)

hierarchical (1)}

(FTAM hierarchical file model)

constraint set {iso standard 8571 constraint-set (4)

sequential- flat (2)}

(FTAM sequential flat constraint set

file contents:

Datatypel : := PrimType -- as defined in Annex 6 A, Part 3

Datatype2 : := CHOICE { Node-Descriptor-Data-Element

Enter-Subtree-Data-Element , ExitSubtree-Data-Element

}

6-37
3. Scope and field of application

The document type defines the contents of a file for storage, for

transfer and access by FTAM.

Note: Storage refers to apparent storage within the Virtual Filestore.

4. References

ISO 8571, Information Processing Systems - Open Systems

Interconnection - File Transfer, Access and Management

5. Definitions

This definition makes use of the terms data element, data unit and

file access data unit as defined in IS08571-1.

6 . Abbreviations

FTAM File Transfer, Access and Management

7 . Document semantics

The document consists of zero, one or more file access data units,

each of which consists of zero, one or more data elements. The order

of each of these elements is significant.

The document structure takes any of the forms allowed by the FTAM

hierarchical file model as constrained by the sequential flat

constraint set (see table 6.9) These definitions appear in ISO 8571-

2. As additional constraints FADU identity will be limited to begin,

end, first and next.

For a specific file the number of data elements in a data unit is

given by the parameters. Each data element is a data type from the

set of primitive data types defined in the Annex 6. A, Part 3 of this

document. Each data unit contains the same data element types in the

same order as all other data units. These types are determined by the

parameters 0 through 2.

Note: The string length values are the actual number of characters

from the specified character set, they do not include any escape

sequences or overhead from the encoding.

8 . Abstract syntactic structure

The abstract syntactic structure of the document is a hierarchically

structured file as defined in the ASN.l module IS08571 FADU in ISO

8571, in which each of the file access data units has the abstract

syntactic structure of NBS-AS1 as defined by the parameters.

6-38
9 , Definition of transfer

9 . 1 Datatype definitions

The file consists of data values which are of either

a) Datatypel defined in table 6.9, where the PrimType in

the datatype is given by the NBS-AS1 definition; or

b) Datatype2 defined in table 6.9, the ASN.l datatype

declared as "Data-Element" in the ASN.l module IS08571-

FADU.

9 . 2 Presentation data values

The document is transferred as a series of presentation data

values, each of which is either

a) one value of the ASN.l datatype "Datatypel", carrying

one of the data elements from the document. All values

are transmitted in the same (but any ) presentation

context defined to support the abstract syntax name

"asnamel" or

b) a value of Datatype2. All values are transmitted in

the same (but any) presentation context defined to

support the abstract syntax name asname2.

Notes

1. Specific carrier standards may impose additional constraints

on the presentation context to be used, where the above

permits a choice

2. Any document type defined in this entry either makes no use

of Datatype2, or starts with a Datatype2 transmission.

Boundaries between presentation data values in the same

presentation context, and boundaries between P-DATA primitives,

are chosen locally by the sending entity at the time of

transmission, and carry no semantics of the document type.

Receivers which support this document type shall accept a

document with any of the permitted transfer options (e.g. . document type parameters and transfer syntaxes)

9 . 3 Sequence of presentation data values

The sequence of presentation data values of type a) and the

sequence of presentation data values of types a) and b) is the

same as the sequence of data elements within a Data Unit, and

Data Units in the hierarchical structure, when flattened

according to the definition of the hierarchical file model in ISO

8571-2.

6-39
10 . Transfer syntax

11 .

11.1

11 . 1 .

11.2

11.3

An implementation supporting this document type shall support the

transfer syntax generation rules named in table 6.9 for all

presentation data values transferred. An implementation may

optionally support other named transfer syntaxes.

ASE specific specifications for FTAM

Simplification and relaxation

1 Structural simplification

This simplification loses information.

The document type NBS-6 may be simplified to the document type

FTAM-3 (allowed only when reading the file). The octet

representation of the transferred data is unpredictable. It will

usually correspond to the data values as stored in the local Real

Filestore of the Responder.

Access context selection

A document of type NBS-6 may be accessed in any one of the access

contexts defined in the sequential flat constraint set. The

presentation data units transferred in each case are those

derived from the structuring elements defined for that access

context in ISO 8571-2.

The INSERT operation

When the INSERT operation is applied at the end of file the

transferred material shall be the series of FADUs which would be

generated by reading any NBS-6 document with the same parameter

values in access context FA.

I

6-40
NBS Random access file

1. Entry number: NBS -7

2. Information objects
Table 6.10 Information objects in NBS-7

document type name {iso identified-organization icd (9999)

organ-code (1) document type (5) randomfile (7)} (NBS FTAM random access file)

abstract syntax names:

a) name for asnamel

b) name for asname2

{iso identified-organization icd (9999)

organ-code (1) abstract -syntax (2) nbs-asl

(0))

(NBS abstract syntax AS1)

{iso standard 8571 abstract- syntax( 2) ftamfadu (2)} (FTAM FADU)

transfer syntax names: { joint-iso-ccitt asnl (1) basic-encoding (1)

} (Basic Encoding of a single ASN.l type)

parameter syntax:

PARAMETERS : := SEQUENCE OF CHOICE { Parameter0 , Parameterl , Parameter2)

ParameterO : := universal-class-number-0 [0] INTEGER {univer-time (23)

,

gen-time (24)

,

boolean (1)

,

null (5) } Parameterl : := [1] SEQUENCE { universal-class-number- 1 INTEGER { int (2),

bit (3),

ia5 (22),

graphic (25),

general (27)

,

octet (4) }

,

string- length INTEGER } Parameter : := [2] SEQUENCE { private-class-number INTEGER {float (0)},

length- 1 INTEGER,

length- 2 INTEGER }

file model {iso standard 8571 file-model (3)

hierarchical (1)}

(FTAM hierarchical file model)

constraint set {iso identified-organization icd (9999)

organ-code ( 1 ) constraint-set (4) nbs-ordered

-flat(2)} (NBS ordered flat constraint set)

file contents:

Datatype 1 : := PrimType -- as defined in Annex 6 A, Part 3

Datatype2 : := CHOICE { Node-Descriptor-Data-Element

Enter-Subtree-Data-Element } Exit-Subtree-Data-Element }

6-42
3. Scope and field of application

The document type defines the contents of a file for storage, for

transfer and access by FTAM.

Note: Storage refers to apparent storage within the Virtual Filestore.

4 . References

ISO 8571, Information Processing Systems - Open Systems

Interconnection -File Transfer,' Access and Management

5 . Definitions

This definition makes use of the terms data element, data unit and

file access data unit as defined in IS08571-1.

6 . Abbreviations

FTAM File Transfer, Access and Management

7 . Document semantics

The document consists of zero, one or more file access data units,

each of which consists of zero, one or more data elements. The order

of each of these elements is significant.

The document structure takes any of the forms allowed by the FTAM

hierarchical file model as constrained by the NBS-ordered-flat

constraint set (see table 6.10). These definitions appear in Appendix

6 A, Part 2 of this document.

For a specific file the number of data elements in a data unit is

given by the parameters. Each data element is a data type from the

set of primitive data types defined in the Annex 6. A, Part 3 of this

document. Each data unit contains the same data element types in the

same order as all other data units. These types are determined by the

parameters 0 through 2.

Note: The string length values are the actual number of characters

from the specified character set, they do not include any escape

sequences or overhead from the encoding.

8 . Abstract syntactic structure

The abstract syntactic structure of the document is a hierarchically

structured file as defined in the ASN.l module IS08571 FADU in ISO

8571, in which each of the file access data units has the abstract

syntactic structure of NBS-AS1 as defined by the parameters.

6-43
9. Definition of transfer

91 Datatype definitions

The file consists of data values which are of either

a) Datatypel defined in table 6.10, where the PrimType in

the datatype is given by the NBS-AS1 definition; or

b) Datatype2 defined in table 6.10, the ASN.l datatype

declared as "Data-Element" in the ASN.l module IS08571-

FADU.

9 . 2 Presentation data values

The document is transferred as a series of presentation data

values, each of which is either

a) one value of the ASN.l datatype "Datatypel", carrying

one of the data elements from the document. All values

are transmitted in the same (but any ) presentation

context defined to support the abstract syntax name

"asnamel" or

b) a value of " Datatype2". All values are transmitted in

the same (but any) presentation context defined to

support the abstract syntax name " asname2".

Notes:

1. Specific carrier standards may impose additional constraints

on the presentation context to be used, where the above

permits a choice

2. Any document type defined in this entry either makes no use

of Datatype2, or starts with a Datatype2 transmission.

Boundaries between presentation data values in the same

presentation context, and boundaries between P-DATA primitives,

are chosen locally by the sending entity at the time of

transmission, and carry no semantics of the document type.

Receivers which support this document type shall accept a

document with any of the permitted transfer options (e.g.

document type parameters and transfer syntaxes)

9 . 3 Sequence of presentation data values

The sequence of presentation data values of type a) and the

sequence of presentation data values of types a) and b) is the

same as the sequence of data elements within a Data Unit, and

Data Units in the hierarchical structure, when flattened

according to the definition of the hierarchical file model in ISO

8571-2.

6-44
10 . Transfer syntax

11 .

11.1

11 . 1 .

11.2

11.3

An implementation supporting this document type shall support the

transfer syntax generation rules named in table 6.10 for all

presentation data values transferred. Implementation may

optionally support other named transfer syntaxes.

ASE specific specifications for FTAM

Simplification and relaxation

1 Structural simplification

This simplification loses information.

The document type NBS-7 may be simplified to the document type

FTAM-3 (allowed only when reading the file) . The octet

representation of the transferred data is unpredictable. It will

usually correspond to the data values as stored in the local Real

Filestore of the Responder.

Access context selection

A document of type NBS-7 may be accessed in any one of the access

contexts defined in the NBS-ordered-flat constraint set. The

presentation data units transferred in each case are those

derived from the structuring elements defined for that access

context in ISO 8571-2.

The INSERT operation

When the INSERT operation is applied at the end of file the

transferred material shall be the series of FADUs which would be

generated by reading any NBS-7 document with the same parameter

values in access context FA.

6-45
NBS Indexed sequential file

1. Entry Number: NBS -8

2. Information objects

Table 6.11 Information objects in NBS -8

document type name {iso identified-organization icd (9999)

organ-code (1) document type (5) indexedf lie (8)}

(NBS FTAM indexed file)

abstract syntax names:

a) name for asnamel

b) name for asname2

{iso identified-organization icd (9999)

organ-code (1) abstract -syntax (2) nbs-asl

(0)}

(NBS abstract syntax AS1)

{iso standard 8571 abstract- syntax( 2) ftamfadu ( 2 )

}

(FTAM FADU)

transfer syntax names: { joint-iso-ccitt asnl (1) basic-encoding (1)

} (Basic Encoding of a single ASN.l type)

parameter syntax:

PARAMETERS : := SEQUENCE {DataTypes, KeyType , KeyPosition)

DataTypes : := SEQUENCE OF CHOICE {ParameterO, Parameterl , Parameter2}

KeyType : := CHOICE {ParameterO, Parameterl, Parameter2}

ParameterO, Parameterl, Parameter2, as defined for the

document types NBS -6, NBS -7

KeyPosition: := position INTEGER

file model {iso standard 8571 file-model (3)

hierarchical (1)}

(FTAM hierarchical file model)

constraint set {iso standard 8571 constraint-set (4)

ordered-flat (3) ) (FTAM ordered flat constraint set)

file contents:

Datatype 1 : := PrimType -- as defined in Annex 6 A, Part 3

Datatype2 : := CHOICE { Node-Descriptor-Data-Element

,

Enter-Subtree-Data-Element } Exit-Subtree-Data-Element }

6-46
3. Scope and field of application

The document type defines the contents of a file for storage, for

transfer and access using FTAM.

Note: Storage refers to apparent storage within the Virtual Filestore.

4. References

ISO 8571, Information Processing Systems - Open Systems

Interconnection -File Transfer, Access and Management

5 . Definitions

This definition makes use of the terms data element, data unit and

file access data unit as defined in IS08571-1.

6 . Abbreviations

FTAM File Transfer, Access and Management

7 . Document semantics

The document consists of zero, one or more file access data units,

each of which consists of zero, one or more data elements. The order

of each of these elements is significant.

The document structure takes any of the forms allowed by the FTAM

hierarchical file model as constrained by the FTAM ordered flat

constraint set (see table 6.11). These definitions appear in IS08571-

2 .

The following additional requirements are specified for the use of the

ordered flat constraint set:

o The FADU identities 'first', 'last', and 'traversal' number

are not required for conformant implementations

o The identities 'next' and 'previous' are allowed for all

FADU's

Each data element is a data type from the set of primitive data types

defined in Appendix 6A, Part 3 of this document. Each data unit

contains the same data element types in the same order as all other

data units. These types and their respective maximum lengths are

defined by the <DataTypes> parameter.

Note: The length values refer to the number of characters from the

applicable type, not to the number of octets in the encoding, nor to

the line length in any rendition of the document, where these are

different

6-47
Each data unit in the file has a key associated with it. The key of

each data unit is of the same data type as the key of all other data

units in the file and is a single data element from the set of

primitive data types defined in Appendix 6A, Part 3.

The type and length of the key are defined by the <KeyType> parameter.

The primitive data types and minimum size ranges of each unit which an

implementation must accept as a key value are given in the following

table 6.12.

Table 6.12 Datatypes for keys

Key Type Minimum Range (octets) Order

ASN.l Integer (1-2) increasing numeric value

ANS.l IA5String (0-16) lexical order

ASN.l Graphicstring (0-16) lexical order

ANS.l GeneralString (0-16) lexical order

ANS.l Octetstring (0-16) increasing value

ASN.l General izedTime increasing time value

ASN.l UniversalTime increasing time value

NBS-AS2 Float ingPointNumber increasing numeric value

The position of the key in the data unit is specified by the

<position> parameter.

position = 0 implies the key is not part of the data

position > 0 specifies the actual data element in the data unit.

8 . Abstract syntactic structure

The abstract syntactic structure of the document is a hierarchically

structured file as defined in the ASN.l module IS08571 FADU in ISO

8571, in which each of the file access data units has the abstract

syntactic structure of NBS-AS1 as defined by the parameters.

9. Definition of transfer

9.1 Datatype definitions

The file consists of data values which are of either

a) Datatypel defined in table 6.11, where the PrimType in the

datatype is given by the NBS-AS1 definition; or

b) Datatype2 defined in table 6.11, the ASN.l datatype declared

as "Data-Element" in the ASN.l module IS08571-FADU.

6-48
9.2 Presentation data values

The document is transferred as a series of presentation data

values, each of which is either

a) one value of the ASN.l datatype "Datatypel", carrying one of

the data elements from the document. All values are

transmitted in the same (but any) presentation context

defined to support the abstract syntax name "asnamel" or

b) a value of "Datatype2". All values are transmitted in the

same (but any) presentation context defined to support the

abstract syntax name asname2.

Notes

1. Specific carrier standards may impose additional constraints

on the presentation. context to be used, where the above

permits a choice

2. Any document type defined in this entry either makes no use

of Datatype2, or starts with a Datatype2 transmission.

Boundaries between presentation data values in the same

presentation context, and boundaries between P-DATA primitives,

are chosen locally by the sending entity at the time of

transmission, and carry no semantics of the document type.

Receivers which support this document type shall accept a

document with any of the permitted transfer options (e.g.

document type parameters and transfer syntaxes)

9 . 3 Sequence of presentation data values

The sequence of presentation data values of type a) and the

sequence of presentation data values of types a) and b) is the

same as the sequence of data elements within a Data Unit, and

Data Units in the hierarchical structure, when flattened

according to the definition of the hierarchical file model in ISO

8571-2.

10. Transfer syntax

An implementation supporting this document type shall support the

transfer syntax generation rules named in table 6.11 for all

presentation data values transferred. Implementation may

optionally support other named transfer syntaxes.

11. ASE specific specifications for FTAM

11.1

11.1.1

Simplification and relaxation

Structural simplification

;

6-49
This simplification loses information.

The document type NBS-8 may be accessed as a document type FTAM

(allowed only when reading the file) by specifying document type

FTAM-3 in the <Contents Type> parameter in F-OPEN request, and

limiting access context to UA on F READ.

The octet representation of the transferred data is

unpredictable. It will usually correspond to the data values as

stored in the local Real Filestore of the Responder.

A document of type NBS-8 can be accessed as a document of type

NBS-6 (allowed only when reading the file) by specifying document

type NBS-6 with appropriate data type parameters in the CContents

Type> parameter on the F-OPEN request. The traversal order of

the FADUs must be maintained.

Note: The traversal order is as reading the file as NBS-8 in key

order.

11.2 Access context selection

A document of type NBS-8 may be accessed in any one of the access

contexts defined in the FTAM ordered flat constraint set. The

presentation data units transferred in each case are those

derived from the structuring elements defined for that access

context in ISO 8571-2.

11.3 The INSERT operation

When the INSERT operation is applied the transferred material

shall be the series of FADU which would be generated by reading

any NBS-8 document with the same parameter values in access

context FA.

The insertion of a new FADU after an already existing FADU will

be indicated via a diagnostic on TRANSFER-END.

11.4 The EXTEND operation

This operation is excluded for the use with this document type.

6-50
NBS File directory file

1. Entry Number: NBS -9

2 . Information obj ects
Table 6.12 Information objects in NBS-9

document type name {iso identified-organization icd (9999) organ

-code (1) document- type (5) file directory

(9)}

(NBS FTAM file directory file)

abstract syntax names: {iso identified-organization icd (9999) organ

-code (1) abstract- syntax (2) nbs-as2 (1))

(NBS file-directory entry abstract syntax)

transfer syntax names: { joint-iso-ccitt asnl (1) basic -encoding (1)}

(Basic Encoding of a single ASN.l type)

parameter syntax

PARAMETERS : := attribute -names [0] IMPLICIT BIT STRING {

-- Kernel group

read_filename (0) , read_permitted- actions (1),

read_contents- type (2),

-- Storage group

read_storage- account (3),

read_date-and- time-of-creation (4)

,

read_date-and- time-of - last -modification (5)

,

read_date-and-time-of-last-read-access (6)

,

read_date-and- time -of -last -attribute -modification( 7)

,

read_identity-of-creator (8),

read_identity-of -last-modifier (9)

,

read__identity-of = last-reader (10) , read__identity-of- last-attribute-modifier (11)

,

read_file- availability (12),

read_filesize (13),

read_future-filesize (14),

-- Security group

read_access-control (15),

read_legal-qualifications (16),

-- Private group

read_private-use (17) }

(Continued on next page.)

6-52
Table 6.12 Information objects in NBS-9 continued.

file model {iso standard 8571 file-model (3)

hierarchical (1)) FTAM hierarchical file

(FTAM hierarchical file model)

constraint-set {iso standard 8571 constraint-set (4)

unstructured (1)} FTAM unstructured

(FTAM unstructured constraint set)

File contents:

Datatypel : := FileDirectoryEntry

--As defined by NBS-AS2 in Appendix A,

--Part 3 of this document

3. Scope and field of Application

This document defines the contents of a file for transfer (not for

storage) using FTAM.

4 . References

ISO 8571, Information Processing Systems - Open Systems

Interconnection -File Transfer, Access and Management.

5 . Definitions

This definition makes use of the terms data element, data unit and

file access data unit as defined in ISO 8571-1

6 . Abbreviations

FTAM File Transfer, Access and Management.

7 . Document Semantics

The document consists of one file access data unit, which consists

only of zero, one or more data elements of type <FileDirectoryEntry>

(defined in NBS-AS2)

The document structure takes any of the forms allowed by the FTAM

hierarchical file model as constrained by the unstructured constraint

set. These definitions appear in ISO 8571-1.

The parameter of the document type is used on F-OPEN request to

specify the desired attributes of each of the files on the filestore,

when reading the document.

;

6-53
8 . Abstract syntactic structure

The abstract syntactic structure of the document is a series of file

directory entries, each of which is defined by the

<FileDirectoryEntry> definition in NBS-AS2.

Additional constraints are defined for this document type: File

access actions are restricted to Read. File-directory files may be

Selected, Opened, Read, Closed, and Deselected. They may not be

Created or Deleted. They may not be Written or Modified (except as a side effect of actions performed on individual files contained within

a file directory)

9 . Definition of transfer

9 . 1 Datatype definition

The file consists of zero or more values of Datatypel defined in

table 6.13.

9.2 Presentation data values

The document is transferred as a series of presentation data

values. Each presentation data value shall consist of one value

of the ASN.l data type "Datatypel" , carrying one of the file

directory entries from the document.

All values are transmitted in the same (but any) presentation

context established to support the abstract syntax name "asnamel"

declared in table 6.13.

9 . 3 Sequence of presentation data values

The sequence of presentation data values is the same as the

sequence of file directory entries within the Data Unit in the

file.

10. Transfer syntax

An implementation supporting this document type shall support the

transfer syntax generation rules named in table 6.13 for all

presentation data values transferred. Implementations shall

optionally support other named transfer syntaxes.

11. ASE specific specifications for FTAM

11.1 Simplification and relaxation

Relaxation is allowed to any bitstring combination of the

document type parameter.

6-54
Part 2: Constraint Sets

NBS Ordered flat constraint set

1 . Field of application

The NBS-ordered flat constraint set applies to files which are

structured into a sequence of individual FADUs and to which access may

be made on an FADU basis by position in the sequence.

2. Basic constraints

]

6-55
Table 6,14 Basic constraints for NBS Ordered flat

Constraint set descriptor NBS Ordered flat

Constraint set identifier {iso identified-organization icd (9999)

organ-code (1) constraint-set (4) nbsordered-flat (2)}

Node name None

File access actions Locate, Read, Insert, Erase, Replace

Qualified action None

Available access contexts HA, FA, UA

Creation state Root node without an associated data

unit

Location after open Root node

Beginning of file Root node

End of file No node selected; "previous" gives last

node in traversal sequence , current and

next give an error.

Read whole file Read in access context FA or UA with

FADU identity of "begin"

Write whole file (append)

Write whole file (replace)

- y

Transfer the series of leaf FADUs which

would be generated by reading the whole

file in access context FA; perform the

transfer with an FADU identity of "end"

and a file access action of "insert".

Transfer the series of leaf FADUs which

would be generated by reading the whole

file in access-context HA; perform the

transfer with FADU identity "begin" and

file action of "replace".

3 . Structural constraints

The root node shall not have an associated data unit; all children of

the root node shall be leaf nodes and may have an associated data

unit; all arcs from the root node shall be of length one.

6-56
4. Action constraints

Insert: The Insert action is allowed only at the end of file. If the

FADU identity is "end" the new node is inserted following all existing

nodes in the file. If the FADU identity is "traversal number", the

number must be at least one greater than the traversal number of the

last existing node. Any nodes between the last existing node and the

new node are empty, i.e. nodes without data. If the FADU identity is a "traversal number" not greater than that of the last existing node,

an error will occur.

EraseThe Erase action is only allowed at the root node to empty the

file, with FADU identity of "begin". The result is a solitary root

node without an associated data unit.

Note: It is the intention when using this constraint set to allow for

emptying an FADU, i.e. leaving an FADU with a DU of data length 0 (or

without a DUO; afterwards data may reinserted into this hole. In

order to empty an FADU, the replace operation may be used with access

context UA and data length zero (or with access context HA, when the

<data exists> bit is set to <false> (and no DU) . Refilling the hole

is accomplished by a Replace operation with access context UA and the

new DU (or with access context HA, when the <data exists> bit is set

to <true> and the new DU)

5 . Identity constraints

The FADU identity associated with the file action shall be one of the

identities begin, end, first, last, current, next, previous or a

traversal number greater than or equal to one. The actions with which

these identities can be used are given in the following table.

Table 6.15 Identity constraints in NBS Ordered flat

Action Begin End First Last Current Next Previous Traversal

Locate valid valid valid valid valid valid valid valid

Read whole leaf leaf leaf leaf leaf leaf

Insert valid

Erase whole

Replace leaf leaf leaf leaf leaf leaf

/

6-57
Part 3: Abstract Syntaxes

Abstract Syntax NBS-AS1

Abstract syntax name: {iso identified-organization nbs (0) ftam (1)

abstract -syntax (2) nbs-asl (0)}

"NBS abstract syntax AS1"

This is an abstract syntax for the set of presentation data values

of which is a value of the ASN.l type NBS -AS 1 . PrimType

each

NBS -AS 1 DEFINITIONS : BEGIN

PrimType : := CHOICE { INTEGER,

BIT STRING,

BOOLEAN

,

IA5String,

Graphicstring,

GeneralString,

OCTET STRING,

UTCTime

,

GeneralizedTime

,

NULL,

FloatingPointNumber }

The support for IA5String is the IAS GO

character set and

the IA5 CO set

The minimum level of support for

Graphicstring is the

IAS GO character set and the 8859-1 GO and G1

sets

The minimum level of support for

GeneralString is the

IA5 GO character set and the 8859-1 GO and G1

character sets, and IA5 CO set.

FloatingPointNumber : := [PRIVATE 0]

finite

{

CHOICE { [0] IMPLICIT SEQUENCE

Sign,

mantissa BIT STRING

first bit must be 1 exponent INTEGER)

,

infinity [1] IMPLICIT Sign,

signalling-nan [2] IMPLICIT NaN,

quiet-nan [3] IMPLICIT NaN,

zero [4] IMPLICIT NULL } Sign : := INTEGER { positive (0), negative (1) } NaN ::= INTEGER

END

For this abstract syntax the following transfer syntax can be used

6-58
{ joint-iso-ccitt asnl (1) basic-encoding (1)}

(Basic Encoding of a single ASN.l type)

Notes: 1.

2 . 3.

4.

5.

The mantissa is a number in the range (1/2 <mantissa<l )

The value is equal to mantissa * 2 exPonent . The first bit in the mantissa is most significant.

See IEEE 754 for definitions of terminology, such as NaN.

A minimum length range (in bits) is required for the

components of <FloatingPointNumber>, as follows: mantissa 1-

23 bits, and exponent 0-8 bits.

Abscract Syntax NBS-AS2

Abstract syntax name: { iso identified-organization icd (9999)

organ-code (1) abstract-syntax (2)

nbs-as2 (2) }

(NBS file directory entry abstract syntax)

This is an abstract syntax for the set of presentation data values, each

of which is a value of the ASN.l Type NBS-AS2 FileDirectoryEntry

NBS-AS2 DEFINITIONS : :=

BEGIN

•

i FileDirectoryEntry : :=[PRIVATE 2] Read-Attributes

Read-Attributes : :=IS08571-FTAM. Read-Attributes

i END

For this abstract syntax the following transfer syntax will be used

{ joint-iso-ccitt asnl (1) basic-encoding (1) }

(Basic Encoding of a single ASN.l type)

Abstract Syntax (FTAM unstructured text abstract syntax)

This abstract syntax is defined as DataTypel (File Contents) in Table 19

of ISO 8571-2, Annex B.

Abstract Syntax (FTAM unstructured binary abstract syntax)

This abstract syntax is defined as DataTypel (File Contents) in Table 21

of ISO 8571-2, Annex B.

6-59
6.22 APPENDIX B: KNOWN ERRORS IN ISO AND GCITT DOCUMENTS

This appendix lists errors that are known in ISO and GCITT documents

Known errors are removed from this appendix when corrected text is

available from ISO and GCITT. This appendix is for information only
7. CCITT 1984 X.400 BASED MESSAGE HANDLING SYSTEM

7 . 1 INTRODUCTION

This is an implementation agreement developed by the Implementor's

Workshop sponsored by the U.S. National Bureau of Standards to promote

the useful exchange of data between devices manufactured by different

vendors. This agreement is based on, and employs protocols developed

in accord with, the OSI Reference Model. While this agreement

introduces no new protocols, it eliminates ambiguities in

interpretations

This is an implementation agreement for a Message Handling System

(MHS) based on the X. 400-series of Recommendations (1984) and Version

5 of the X.400 Series Implementor's Guide from the CCITT. It is

recommended that product vendors consult later versions of this guide.

Figure 7.1 displays the layered structure of this agreement.

This agreement can be used over any Transport protocol class. In

particular, this MHS agreement can be used over the Transport protocol

class 0 used over CCITT X.25, described in section 4.6 of this

document. In addition, this MHS agreement can be used over the

Transport profiles used in support of MAP (Manufacturing Automation

Protocol) or TOP (Technical and Office Protocols) . Note that the MAP

or TOP environment must support the reduced Basic Activity Subset

(BAS) as defined in X.410.

The UAs and MTAs require access to directory and routing services. A

Directory Service is to be provided for each (vendor-specific) domain.

Except insofar as they must be capable of providing addressing and

routing described hereunder, these services and associated protocols

are not described by this agreement.

User Agent Layer CCITT X. 420

Message Transfer Agent Layer CCITT X. 411

Reliable Transfer Service Layer CCITT X.410

Presentation Layer CCITT X.410 sec. 4.2

Session Layer See Section 5.1.1

Figure 7.1 The layered structure of this implementation agreement

7-1
7 . 2 SCOPE

This agreement applies to Private Management Domains (PRMDs) and

Administration Management Domains (ADMDs). Four boundary interfaces

are specified:

(A) PRMD to PRMD

(B) PRMD to ADMD

(C) ADMD to ADMD.

(D) MTA to MTA (within a PRMD, e.g., for MTAs from different

vendors .

)

In case A, the PRMDs do not make use of MHS services provided by an

ADMD. In cases B and C, UAs associated with an ADMD can be the source

or destination for messages. Furthermore, in cases A and B, a PRMD

can serve as a relay between MDs , and in cases B and C an ADMD can

serve as a relay between MDs. Figure 7.2 illustrates the interfaces

to which the agreement applies.

X.400 protocols other than the Message Transfer Protocol (PI) and the

Interpersonal Messaging Protocol (P2) are beyond the scope of this

agreement. Issues arising from the use of other protocols or relating

to PI components in support of other protocols are outside the scope

of this document. This agreement describes the minimum level of

services provided at each interface shown in Figure 7.2. Provision

for the use of the remaining services defined in the X.400 Series of

Recommendations is outside the scope of this document.

With the exception of intra domain connections, this agreement does

not cover message exchange between communicating entities within a

domain even if these entities communicate via PI or P2 . Bilateral

agreements between domains may be implemented in addition to the

requirements stated in this document. Conformance to this agreement

requires the ability to exchange messages without use of bilateral

agreements

/

7-2
PRMD = Private Management Domain

ADMD = Administration Management Domain

PRMD

PRMD

MTA A — D

MTA B

A

B

PRMD

ADMD

ADMD

B

-C

Figure 7.2 This agreement applies to the interface between: (A)

PRMD and PRMD; (B) PRMD and ADMD; (C) ADMD and ADMD;

and (D) MTA and MTA

7.3

STATUS

This version of the X.400 based Message Handling System implementation

agreements was completed on December 12, 1986. No further

enhancements will be made to this version. See the next

section- -Errata.

7.4

ERRATA

7,5

PRMD to PRMD

7.5.1 Introduction

This section is limited in scope to issues arising from the direct

connection (interface A in Figure 7.2) of two PRMDs . "Direct" means

that no ADMD or relaying PRMD provides MHS services to facilitate

message interchange. "Direct" does not exclude those instances for

which Administrations happen to be ADMDs but are not providing X.400

services, that is, they are used only to provide lower layer services

such as X.25. Figure 7.3 schematically represents the scope of this

section.

These issues relate to the use of the UAL (User Agent Layer) and MTL

(Message Transfer Layer) services, protocol elements, recommended

practices and constraints. In particular, this section addresses the

PI and P2 protocols and their related services in a direct connection

environment. This section describes the minimum level of services

7-3
provided by a PRMD. Provision for the use of the remaining services

defined in the X.400 Series of Recommendations is beyond the scope of

this section.

Private Domain X

i—

UA

MTA

<

<

/ \

the

|remainder of!; !;:Domain X

Network

P2

PI

Private Domain Y

>

Pthe:

|remainder of

Domain Y

JnETWORK

UA

MTA

/ \

Figure 7.3 Interconnection of private domains

7.5.2 Service Elements and Optional User Facilities

This section identifies those service elements and optional user

facilities that must be provided in support of PI and P2

7 . 5 . 2 .

Classification of Support for Services

The classification of UA and MT-Service elements is used to

define characteristics of equipment. Equipment can claim

SUPPORT or NON-SUPPORT of a Service; in the case of

UA-service elements, a separate classification is given for

Origination and Reception.

The service provider is defined as the entity providing the

service, in this case, the MTL or the UAL. The service user

is either the MHS user or the UAL. The classification of

provider and user relates to the sublayer for which the

service element is defined.

7-4
7 . 5 . 2 . 1 . 1 Support (S)

a) Support means

o The service provider makes the service

element available to the service user.

o The service user gives adequate support to

the MHS to invoke the service element or

makes information associated with the service

element available.

b) Support for Origination means that:

o The service provider makes the service

element available to the service user for

invocation.

o The service user gives adequate support to

the end user of the MHS to invoke the service

element

c) Support for Reception means that:

o The service provider makes information

associated with the service element available

to the service user.

Note: A UA- or MT- service element can carry information

from originator to recipient only if:

o the service element is available to the

originator

,

o the service element is available to the

recipient, and

o all intermediate steps carry the information.

7 , 5 , 2 . 1 .Non Support (N)

This means that the service provider is not required to

make the service element available to the service user.

However, the service provider should not regard the

occurrence of the corresponding protocol elements as an

error and should be able to relay such elements.

Implementations making a profile available should

indicate deviations (additions or deletions) with

respect to the requirement in the profile.

;

7-5
7.5.2. 1.3 Not Used (N/U)

This means that although the Recommendation allows this

service element, this profile does not use it.

7 . 5 . 2 . 1 .

Not Applicable (N/A)

This means that this service element does not apply in

this particular case (for originator or recipient)

7 . 5 . 2 .Summary of Supported Services

a) Within a PRMD, a User Agent must support all P2 BASIC

I PM Services (X.400) and all P2 ESSENTIAL I PM Optional

user facilities (X.401) subject to the qualifiers

listed in Appendix 7A.

b) Within a PRMD, a MTA must support all BASIC MT Services

(X.400) and all ESSENTIAL MT optional user facilities

(X.401) subject to the qualifiers listed in Appendix

7A.

c) No support is required of the additional optional user

facilities of X.401.

7 . 5 . 2 .

MT Service Elements and Optional User Facilities

Tables 7.4 through 7.6 show the message transfer (MT)

service elements and optional user facilities.

Table 7.4 Basic MT service elements

Service Elements

Support (S) or

Non-support (N)

1 Access Management N/U x Content Type Indication S

Converted Indication S

Delivery Time Stamp Indication S

Message Identification S

Non-delivery Notification S

Original Encoded Information Types Indication S

Registered Encoded Information Types N/U^

Submission Time Stamp Indication S

Not applicable to co-resident UA and MTA.

7-6
Table 7.5

/

MT optional user facilities provided to the UA-selectable on a per-message basis

Support (S) or

MT Optional User Facilities Categorization Non-support (N)

Alternate Recipient Allowed E S

Conversion Prohibition E S

Deferred Delivery E N

2

Deferred Delivery Cancellation E N

2

Delivery Notification E S

Disclosure of Other Recipients E N

3

Explicit Conversion A N

Grade of Delivery Selection E S

Multi-destination Delivery E S

Prevention of Non-delivery Notification A n4

^e?urn of Contents S

Table 7.6 MT optional user facilities provided to the UA agreed for

any contractual period of time

MT Optional User Facilities Categorization

Support (S) or

Non-Support (N)

Alternate Recipient Assignment A N

Hold for Delivery A N/U

Implicit Conversion’ A N

E: Essential optional user facility.

A: Additional optional user facility.

2 A local facility subject to qualifiers in Appendix 7A.

3 Support not required for an originating MT user; support must be

provided for recipient MT users.

^ Subject to qualifiers in Appendix 7A.

;

7-7
7 . 5 . 2 . 4 IPM Service Elements and Optional User Facilities

Tables 7.7 through 7.9 show the IPM service elements and

optional user facilities.

Table 7.7 Basic IPM service elements

Service Elements

Origination

by UAs

Reception

by UAs

Access Management N/U5 N/U5

Content Type Indication S S

Converted Indication N/A S

Delivery Time Stamp Indication N/A s Message Identification S s Non-delivery Notification S N/A

Original Encoded Information S S

Types Indication

Registered Encoded Information Typ es N/A N/A5

Submission Time Stamp Indication S S

IP-message Identification S S

Typed Body S s

Does not apply to co- resident UA and MTA.

Table 7.8 IPM optional facilities agreed for a contractual period of

time

Service Elements Categorization

Support (S) or

Non-Support (N)

Alternate Recipient Assignment A N

Hold for Delivery A N

Implicit Conversion A N

7-8
Table 7.9 IPM optional user facilities selectable on a per-raessage basis

IPM Optional User Facilities

Origination

by UAs

Reception

by UAs

Alternate Recipient Allowed A (N) A (N)

Authorizing Users Indication A (N) E (S)

Auto -forwarded Indication A (N) E (S)

Blind Copy Recipient Indication A (N) E (S)

Body Part Encryption Indication A (N) E (S)

Conversion Prohibition E (S) E (S)

Cross-referencing Indication A (N) E (S)

Deferred Delivery E (N) 6 N/A

Deferred Delivery Cancellation A (N/U) 6 N/A

Delivery Notification E (S) N/A

Disclosure of Other Recipients A (N) E (S)

Expiry Date Indication A (N) E (S)

Explicit Conversion A (N) N/A

Forwarded IP-message Indication A (N) E (S)

Grade of Delivery Selection E (S) E (S)

Importance Indication A (N) E (S)

Multi-destination Delivery E (S) N/A

Multi-part Body A (N) E (S)

Non-receipt Notification A (N) A (N)

Obsoleting Indication A (N) E (S)

Originator Indication E (S) E (S)

Prevention of Non-delivery Notification A (N) N/A

Primary and Copy Recipients Indication E (S) E (S)

Probe A (N) N/A

Receipt Notification A (N) A (N)

Reply Request Indication A (N) E (S)

Replying IP-message Indication E (S) E (S)

Return of Contents A (N) N/A

Sensitivity Indication A (N) E (S)

Subject Indication E (S) E (S)

£° A local facility subject to

7.5.3 X.400 Protocol

qualifiers in Appendix 7A.

Definitions

This section reflects the agreements of the NBS/OSI Workshop

regarding PI and P2 protocol elements.

1

7-9
7 . 5 . 3 .

Protocol Classification

The protocol classifications are defined below in table

7.10:

1) UNSUPPORTED = X

These elements may be generated, but no specific processing should

be expected in a relaying or delivering domain. A relaying domain

must at least relay the semantics of the element. The absence of

these elements should not be assumed, in a relaying or delivering

domain, to convey any significance.

2) SUPPORTED = H

These elements may be generated. However, implementations are not

required to be able to generate these elements. Appropriate

actions shall be taken in a relaying or delivering domain.

3) GENERATABLE = G

Implementations must be able to generate and handle these protocol

elements, although they are not necessarily present in all

messages generated by implementations of this profile.

Appropriate actions shall be taken in a relaying or delivering

domain.

4) REQUIRED = R

Implementations of this profile must always generate this protocol

element. However, its absence cannot be regarded as a protocol

violation as other MHS implementations may not require this

protocol element. Appropriate actions shall be taken in a relaying or delivering domain.

5) MANDATORY = M

This must occur in each message as per X.411 or X.420 as

appropriate; absence is a protocol violation. Appropriate actions

shall be taken in a relaying or delivering domain.

Table 7.10 Protocol Classifications

7 . 5 . 3 .General Statements on Pragmatic Constraints

a) Where a protocol element is defined as a choice of

Numeric String and Printable String (i.e.,

Administration Domain Name and Private Domain

Identifier) , then a numeric value encoded as a

printable string is equivalent to the same value

encoded as a numeric string. This does not apply to

the Country Name protocol element.

b) The maximum number of recipients in a single MPDU is

7-10
32K - 1 (that is, 32767). However, no individual

limits on the number of occurrences (recipients) are

placed on the following protocol elements: Authorizing

Users, Primary Recipients, Copy Recipients, Blind Copy

Recipients, Obsoletes and Cross References.

Additionally, there is no limit on the number of Reply

to Users. This is a local matter for the originating

system.

c) Use of strings. A Printable String is defined in terms

of the number of characters, which is the same number

of octets. For T.61 strings the number of octets is

twice the number of characters specified.

d) The ability to generate maximum size elements is not

required, with the exception of the component fields in

the Standard Attribute List, in which case it is

required.

7. 5, 3.

MPDU Size

The following agreements govern the size of MPDUs:

o All MTAEs must support at least one MPDU of at least

two megabyte

o The size of the largest MPDU supported by a UAE is a local matter.

7 . 5 . 3 .PI Protocol Elements

7 . 5 . 3 . 4 .

PI Envelope Protocol Elements

Table 7.11 contains Protocol Elements and their

classes

/

7-11
Table 7.11 PI protocol elements

Element Class Restrictions and Comments

MPDU

UserMPDU G

DeliveryReportMPDU G

ProbeMPDU H

UserMDPU

UMPDUEnvelope M

UMPDUContent M

UMPDUEnvelope

MPDUIdentifier M

originator ORname M

originalEncodedlnformationTypes G

ContentType M

If this field is absent, then the

Encoded Information Type is

"unspecified"

UAContentID H Maximum length = 16 characters.

Priority G

PerMessageFlag G Maximum length = 2 octets.

deferredDel ive ry X

PerDomainBilaterallnfo X No limit on number of occurrences.

Recipientlnfo M Maximum number = 32K - 1 occurrTracelnformation M

ences. More severe limitations are

by bilateral agreement.

UMPDUContent M

MPDUIdentifier

GlobalDomainldentif ier M

IA5String M Maximum length = 32 characters,

PerMessageFlag

graphical subset only. Refer to

T.50 for clarification of graphical

subset

discloseRecipients H

conversionProhibited G

alternateRec ip ientAl lowed H

contentReturnRequest X

(Continued on next page.)

7-12
Table 7.11 PI protocol elements, Continued

Element Class Restrictions and Comments

PerDomainBi lateral Info

CountryName M Maximum length = 3 characters.

AdministrationDomainName M Maximum length = 16 characters.

Bilaterallnfo M Maximum depth = 8; maximum

length = 1024 octets

(including encoding).

Reoipientlnfo

recipient M

Extensionldentifier M Maximum value - 32K - 1 (32767).

perRecipientFlag M Maximum length = 2 octets.

ExplicitConversion X

perRecipientFlag

Respons ibilityFlag M

ReportRequest M

UserReportRequest M

Tracelnformation Reference should be made to

Version 5 of the X.400 Implementor's Guide for information

GlobalDomainldentifier M related to Trace sequencing.

DomainSuppliedlnfo M

DomainSuppliedlnfo

arrival M

deferred X

action M

0=relayed (value) G

l=rerouted (value) H Rerouting is not required.

converted H

previous H

ORName See section 7. 5. 3.

EncodedlnformationTypes

bit string M Delivery can only occur if match

is made with Registered Encoded

Information Types . Individual

vendors may impose limits.

Maximum length = 4 octets.

G3NonBasicParameters X

TeletexNonBasicParameters X

PresentationCapabilities X

(Continued on next page.)

7-13
Table 7.11 PI protocol elements, Continued

Element Class Restrictions and Comments

DeliveryReportMPDU

DeliveryReportEnvelope H

DeliveryReportContent M

DeliveryReportEnvelope

report M

originator M

Trace Informat ion M

DeliveryReportContent

original M

intermediate G See comment at end of table.

UAContentID G

ReportedRecipientlnfo M Maximum number = 32K - 1 occurrences

returned H Can only be issued if specifically

requested in the originating

message

billinglnformation X Maximum depth = 8 ; maximum

length = 1024 octets (including

encoding)

ReportedRecipientlnfo

recipient M

Extensions Identifier M

EerRecipientFlag M

Las tTrace Information M

intendedRecipient H

SupplementaryInformat ion X Maximum length = 64 characters.

Note: This length is subject to

change. Value is pending

- y

verification by the CCITT SG

VIII or IX.

Las tTrace Informat ion

arrival M

converted G

Report M

(Continued on next page.

7-14
Table 7.11 PI protocol elements, continued

Element Class Restrictions and Comments

Report

Deliveredlnfo G Generated if delivery is reported.

Nondeliveredlnfo G Generated if failure to deliver

is reported.

Deliveredlnfo

delivery M

typeofUA R This element must be generated with

a PRIVATE value by PRMDs

NonDe liveredlnfo

ReasonCode M

DiagnosticCode

- H Whenever possible, use a meaningful

diagnostic code.

PfobeEnvelope

* probe M

originator M

ContentType M

UAContentID H Maximum length = 16 characters.

original G If this field is absent, then the

Encoded Information Type is

"unspecified”

Trace Informat ion M

PerMessageFlag G

contentLength H

PerDomainBi lateral Info X

Recipientlnfo M Maximum number = 32K - 1 occurrences

GlobalDomainldentifier

CountryName M Maximum length = 3 characters.

AdministrationDomainName (4) M Maximum length = 16 characters or

digits

PrivateDomainldentifier R Maximum length = 16 characters or

digits. This element must be

generated by PRMDs

End of Definitions
Notes on Table 7.11

Comment on intermediate Tracelnformation in the

DeliveryReportContent in table 7.11: Audit and confirmed reports

should not be requested by other than the originating domain for

two reasons. First, the return path of the report may be

different from the path taken by the original message, and it may

exclude the domain that added the request for audit and confirmed

to the message. Second, if the return path is different from the

path of the original message, the originating domain would

receive intermediate trace information that it did not request.

7 , 5 . 3 .

ORName Protocol Elements

Only form 1 variant 1 0/R names are supported.

Table 7.12 contains ORName protocol elements.

These agreements interpret 1984 X.400 Section 3.4 to mean

that the attributes in the ORName in the MPDU must identify

exactly one UA, and that all the values for the attributes

specified in the ORName must be identical to the values of

the corresponding attributes associated with the recipient

UA. Underspecified names that are unique are deliverable.

Overspecified ORName s , ORNames with mismatching fields, and

ambiguous names are to be non-delivered or sent to the

alternate recipient as appropriate.

7-16
Table 7.12 ORName protocol elements

Element Class Restrictions and Comments

ORName

StandardAttributeList M

DomainDefinedAttributeList X

StandardAttributeList (1)

CountryName R As defined in X.411, Maximum

length = 3 characters.

AdministrationDomainName (4) R Maximum length = 16 characters

or digits.

X121Address X Maximum length = 15 digits.

TerminallD X Maximum length = 24 characters.

PrivateDomainName (2) G Maximum length = 16 characters.

OrganizationName (2) G Maximum length = 64 characters.

UniqueUAIdentifier X Maximum length = 32 digits.

PersonalName G Maximum length of values of subelements = 64 characters.

Note: The possibility that this

value may be reduced to 40

characters is for further

study by the CCITT.

OrganizationalUnit (3) G Maximum length = 32 characters per

occurrence. A maximum of four

occurrences are allowed.

DomainDef inedAttributeList (5) Maximum = 4 occurrences

type M Maximum length = 8 characters.

value M Maximum length = 128 characters.

PersonalName

surName ft Maximum length = 40 characters.

givenName G Maximum length = 16 characters.

initials G Maximum length = 5 characters;

excluding surname initial and

punctuation and spaces.

generationQualifier G Maximum length = 3 characters

(Continued on next page.)

7-17
Table 7.12 ORName Protocol Elements, Continued

Notes

1. The following apply for comparison of the Standard Attributes of

an 0/R Name

a. Lower case is interpreted as upper case (for IA5)

b. Multiple spaces may be interpreted as a single space.

Originating domains shall only transmit single

significant spaces. If multiple spaces are transmitted,

non-delivery may occur.

2. At least one of these must be supplied.

3. These should be sent in ascending sequence, from the least

significant Organizational Unit> (lowest in organization

hierarchy) to the most significant. Only those specified should

be sent. (That is, an unspecified Organizational Unit> should

not be sent along as a field of [null] content, nor zero length,

etc . )

4. This attribute shall contain one space in all ORNames of messages

originated in a PRMD that is not connected to an ADMD, and in

ORNames of recipients reachable only through a PRMD; otherwise,

this attribute shall contain an appropriate ADMD name.

5. Some existing systems which will be accessed via an X.4Q0 service

(whether directly connected using X.400 protocols or otherwise)

may require the provision of addressing attributes which are not

adequately supported by Standard Attributes as defined in these

Agreements. In such cases, Domain Defined Attributes are an

acceptable means of carrying additional addressing information.

Failure to support the specification and relaying of DDAs may

prevent successful interworking with such existing systems until

such time as all systems are capable of relaying and delivery

using only the Standard Attribute list. Specific recommendations

on the use of DDAs for particular applications are in the

Recommended Practices Section 7.12, Appendix B.

7 . 5 . 3 . 6 P2 Protocol Profile (Based on fX.4201)

Tables 7.13 and 7.15 classify the support for the P2

protocol elements required by this profile. The tables

give restrictions and comments in addition to X.420.

Restriction on length is one of the types of restrictions.

The reaction of implementations to a violation of this

restriction is not defined by this Profile.

7-18
7 . 5 . 3 . 6 . 1 P2 Protocol - Heading

Table 7.13 below specifies the support for protocol

elements in P2 Headings.

Table 7.13 P2 heading protocol elements

Element Class Restrictions and Comments

UAPDU

IM- UAPDU G

SR -UAPDU X

IM- UAPDU

Heading M

Body M

Heading - IPMessageld M

originator R

authorizingUsers H

primaryRecipients G At least one of primaryRecipients,

copyRecipients G copyRecipients, or

blindCopyRecipients H

blindCopyRecipients must be

present

inReplyTo G

obsoletes H

crossReferences H

subj ect G Maximum length = 128 T.61

expiryDate H

characters (256 octets); the ability

to generate the maximum size

subject is not required.

replyBy H

replyToUsers H

importance H Appropriate action is for further

sensitivity H

s tudy

Appropriate action is for further

autoforwarded H

s tudy

(Continued on next page.)

7-19
I

Table 7.13 P2 heading protocol elements, continued

Element Class Restrictions and Comments

IPmessageld

ORName H

Pr intab leString M Maximum length = 64 characters.

ORDescriptor

ORName H Specify the ORName whenever it is

possible. See Appendix 7B.

freeformName H Maximum length = 64 characters,

graphical subset only (128 octets.)

telephoneNumber H Maximum length = 32 characters.

This allows for punctuation. It

does not take into account possible

future use by ISDN.

Recipient

“

ORDescriptor M

reportRequest X

replyRequest H

•

Body No limit on number of BodyParts

BodyPart G No limit on length of any BodyPart

or the depth of ForwardedIPMessage

BodyParts nested. Classification is

subject to pending CCITT resolution

SR-UAPDU

nonReceipt H

receipt H

reported M

actualRecipient R

intendedRecipient H

converted X

NonReceiptlnformation

reason M

nonReceiptQualifier H

comments H Maximum length = 256 characters.

returned H May only be issued if specifically

requested by originator.

(Continued on next page.)

7-20
I

Table 7.13 P2 heading protocol elements, continued

Element Class Restrictions and Comments

Receipt Informat ion

receipt M

typeOfReceipt H

Supplementarylnformation X Maximum length = 64 characters.

Note: This value is pending

verification by the CCITT SG

VIII or IX.

End of Definitions

7 . 5 . 3 . 6 ,

P2 Protocol - BodvParts

a) All BodyParts with identifiers in the range 0 up

to and including 16K -1 are legal and should be

relayed. BodyPart identifiers corresponding to

X.121 Country Codes should be interpreted as

described in Note 2 of figure 7.14.

o Implementations are required to generate and

image IASText.

o Implementations should specify the other

BodyPart types supported.

o If an implementation supports a particular

BodyPart type for reception, it should also

be able to support that BodyPart type for

reception if it is part of a ForwardedIPMessage

o For the BodyPart types currently considered,

support for the protocol elements is as

indicated in table 7.15.

b) Privately Defined BodvParts

This section describes an interim means for

identifying privately defined BodyParts. This

section shall be replaced in a future version

taking into account CCITT recommendations with

equivalent functionality.

/

7-21
BodyPart : : = CHOICE { [0] IMPLICIT IA5Text

,

[1] IMPLICIT TLX,

[234] IMPLICIT UKBodyParts

,

[310] IMPLICIT USABodyParts

,

} Where UKBodyParts and USABodyParts are defined as

SEQUENCE { BodyPartNumber , ANY)

BodyPartNumber : := INTEGER

Note 1: In the EncodedlnformationTypes of the PI Envelope, the

undefined bit must be set when a message contains a

privately defined BodyPart. Each UA that expects such

BodyParts should include undefined in the set of

deliverable EncodedlnformationTypes it registers with the

MTA.

Note 2: All BodyPartNumbers assigned must be interpreted relative

to the BodyPart in which they are used, which is that

tagged with the value [310] for those defined within the

United States. The NBS assigns unique message

BodyPartNumbers for privately defined formats within the

United States.

Figure 7.14 X.409 Definition of Privately Defined BodyParts

1

7-22
7 . 5 . 3 . 6 . 3 P2 BodvPart Protocol Elements

Table 7.15 P2 BodyParts

Elements Class Restrictions and Comments

BodyPart

IA5Text G

TLX X

Voice X

G3Fax X

TIFO X

' TTX X

Videotex X

National lyDe fined X

Encrypted X

ForwardedIPMessage H

SFD X

TIF1 X

unidentified X

IA5Text

repertoire H

IA5 String M For rendition of IA5Text see

Appendix 7C.

TLX For further study by CCITT.

Voice

Set For further study by CCITT.

BitString M

G3Fax

numberOfPages X

PI . G3NonBasicParameters X

SEQUENCE (OF BIT STRING) M

BIT STRING H See Note.

PI . G3NonBasicParame ters Support for individual elements is

for further study.

TIFO

T . 73Document M

T. 73ProtocolElement H See Note.

(Continued on next page.)

7-23
Table 7.15 P2 BodyParts , continued

Elements Class Restrictions and Comments

TTX

numberOfPages X

telexCompatible X

PI . TeletexNonBasicParams X

SEQUENCE M

T61String H See Note.

PI . TeletexNonBasicParams

graphicCharac terSe ts X

controlCharac terSets X

pageFormats X

miscTerminalCapabilities X

privateUse X

Videotex

SET For further study by CCITT.

Videotexstring M

NationallyDefined

ANY M

Encrypted

SET For further study by CCITT.

BIT STRING M

ForwardedIPMessage

delivery H

Deliverylnformation H

IM-UAPDU M

Deliverylnformation

PI . ContentType M

originator M

original M

PI . Priority G

DeliveryFlags M

otherRecipients H

thisRecipient M

intendedRec ip ient H

converted X

submission M

(Continued on next page.)

7-24
Table 7.15 P2 BodyParts, continued

Elements Class Restrictions and Comments

SFD

SFD. Document M

TIF1

T73 Document M

T73 . ProtocolElement H See note.

Note: This element is not an addition to the definition of the BodyPart.

It is described here to show that the SEQUENCE may contain zero

elements. A Problem Report has been submitted to the CCITT to

clarify whether this is permissible. The NBS/OSI Workshop will

adopt the CCITT decision.

7.5.4 Reliable Transfer Server (RTS)

7 . 5 . 4 .

Implementation Strategy

Based on X.410 clause 3 and X.411 clause 3.5.

7 . 5 . 4 .RTS option selection

a) The maximum number of simultaneous associations is not

limited in this profile; if the capacity of a system is

exceeded, it should not initiate or accept additional

associations

b) Associations are established by the MTA which has

messages to transfer.

c) Associations are released when they are not needed.

Associations may also be ended prematurely due to

internal problems of the RTS.

d) For both monologue and two way alternate associations,

the initiator keeps the initial turn.

e) When establishing an RTS association, the following

rules apply to the use of parameters in addition to

those in X.410 clause 3.2.1:

Dialogue mode: Monologue must be supported for this

profile; two-way alternate is used only

if both partners agree.
Initial turn: Kept by the initiator of the

association.

f) The 'priority-mechanism' and the ' transfer- time limit'

are regarded as local matters.

7 . 5 . 4 .RTS Protocol Options and Clarifications

Realization of the RTS protocol is subject to the following

rules in addition to those specified in X.410 clause 4:

a) One RTS association corresponds to one or more

consecutive session connections (not concurrent ones)

The first is opened with ConnectionData of type OPEN,

and subsequent ones are opened with type RECOVER.

b) Recovery of a Session connection is only by RTS

initiator

c) Checkpoint size :

o Checkpointing and No Checkpointing should be

supported. Whenever possible, checkpointing

should be used.

o The minimum checkpointSize is 1 (that is, 1024

octets)

d) Window size :

o Minimal value of 1 (if checkpointing is

supported)

o WindowSize = 1 means: After an S -SYNCH-MINOR

request is sent, wait until the confirmation is

received before issuing an S-DATA, S- SYNCH-MINOR,

or S -ACTIVITY- END request.

e) APDUs should not be blocked into one activity.

f) Only one SSDU shall be transferred:

o Between two adjacent minor synch points.

o Between minor synch points and adjacent

S -ACTIVITY- START and S -ACTIVITY- END requests.

o Between S -ACTIVITY- START and S -ACTIVITY- END

without checkpoints.

g) A monologue association is defined as follows:

7-26
o The RTS user responsible for establishing the

association is called the initiator.

o The initiator keeps the initial turn.

o APDUs are transferred in the direction of the

initiator to the recipient only.

o There shall be no token passing.

o Only the initiator can effect an orderly release

of the association.

h) A two-way alternate association is as described in

X. 410

i) In the UserData parameter of the S-U-ABORT, the

Ref lectedParameter will not be used in the

Abortlnformation element.

j) When the S -ACTIVITY-RESUME is used to resume an

activity in the same session connection as the one in

which it started, this must happen immediately after

the activity has been interrupted (i.e., no intervening

activity can occur). Otherwise, X.410 clause 4.3

paragraph 1 may be violated.

k) When S -ACTIVITY-RESUME is used to resume an activity

started in another session connection, the following

conditions must be met:

o The current session connection is of type

"recover"

o The value of OldSessionConnectionldentifier in

S -ACTIVITY-RESUME must match the value of the

SessionConnectionldentifier parameter used in the

S-CONNECT of the prior session connection. This

value is also identical to the

SessionConnectionldentifier in the ConnectionData

(in PConnect, in SS-UserData) for the current

session connection.

o This must occur as the first activity of the next

session connection for the same RTS-association.

It must be the first, otherwise X.410 clause 4.5.1

point 1 is violated.

Note: It is in the same RTS-ASSOCIATION because the use of

S -ACTIVITY-RESUME only makes sense within the scope of one

RTS association.

7-27
l) If the transfer of an APDU is interrupted before the

confirmation of the first checkpoint, the value of the

SynchronizationPointSerialNumber in S -ACTIVITY-RESUME

should be zero, and the S -ACTIVITY-RESUME must be

immediately followed by an S -ACTIVITY-DISCARD

m) In S -TOKEN- PLEAS E , the UserData parameter shall contain

an integer conforming to X.409 which conveys the

priority.

n) The receiving RTS can use the value of the Reason

parameter in the S -U- EXCEPTION -REPORT to suggest to the

sending RTS that it should either interrupt or discard

the current activity. S-U-Exception Reports are

handled as stated in Version 5 of the Implementors

Guide pages 12-13, paragraph E-33.

o) In the case of S-P-ABORT, the current activity (if any)

is regarded as interrupted, rather than discarded.

p) Table 7.16 illustrates the legal negotiation

possibilities allowed by X.410 clause 4.2.1 regarding

checkpoint size and window size.

7-28
Table 7.16 Checkpoint window size of IP

acceptor answer

CS = 0

(or unspecified)

WS unspecified

CS = m

WS = j

(or unspecified)

CS = n

WS = j

(or unspecified)

initiator

proposal

1

CS = 0

(or unspecified)

WS = i

(or unspecified)

legal legal legal

CS = k

WS = i

(or unspecified)

legal legal not allowed

Legend:

o CS means Checkpoints ize

o WS means Windows ize

o i, j, k, m, and n are integer values with the following

relations

0 = m = k < n (values assigned to CS)

0 < j = i (values assigned to WS)

o For unspecified parameters, the default applies. In this

case, the numeric relations apply, that is, the default values

substitutefor the unspecified integer.

7 , 5 . 4 .

RTS Protocol Limitations

The RTS Protocol Limitations for this profile are listed in

table 7.17.

1

7-29
Table 7.17 RTS protocol elements

Element Class Restriction

PConnect M

DataTransferSyntax M Value = 0.

pUserData M

checkpoints ize H

windows ize H

dialogueMode H

ConnectionData M

applicationProtocol G Value = 1

Connect ionData

H Value = 8883.

open G

recover G

open

RTS user data G

recover

SessionConnectionldentifier G

RTS user data

mTAName G Maximum length 32 characters

graphic subset of IA5 only.

password G Maximum length 64 octets

graphic subset of IA5 only.

< null RTS User Data > G Generated if other validation

methods are used.

SessionConnectionldentifier

CallingSSUserReference M Maximum length 64 octets including

encoding = 62 octets of T.61.

CommonReference M

AdditionalReference Informat ion H Maximum length 4 octets including

encoding = 2 octets of T.61.

PAccept G

DataTransferSyntax M Value = 0

pUserData M

checkpoints ize H

windows ize H

Connect ionData M

(Continued on next page.)

7-30
Table 7.17 RTS protocol elements, continued

Element Class Restriction

PRe fuse G

RefuseReason M

SS User Data G See Note

(in S- TOKEN -PLEASE)

Abortlnformation G

(in S-U-ABORT)

AbortReason H

reflec tedParameter X Restricted to 8 bits.

End of Definitions

Note: Generated if supplied by the RTS-user. The RTS use may specify

a priority in the TURN-PLEASE primitive, and if so, it is carried as

the SS-User-Data in S- TOKEN -PLEASE.

7.5.5 Use of Session Services

The session requirements and use of session are covered in

section 5 of this document.

7.5.6 Data Transfer Syntax

This section defines Presentation Transfer Syntax and notation

rules applicable to these agreements. Implementations must

conform EXACTLY as specified in X.409 with no further

restrictions. Appendix 7C defines rendition of IA5 Text and T61

characters

7.6

PRMD to ADMD and ADMD to ADMD

7.6.1 Introduction

This section defines the implementation agreements that apply to

the interface between two management domains when at least one is

an ADMD. A message arriving at an ADMD has either no recipient

within that domain or one or more recipients within that domain.

In the former case, the ADMD serves as a relay between two or

more domains and the actions required of that ADMD are

independent of the nature (PRMD or ADMD) of the domains. In the

latter case, the ADMD is responsible for delivering messages to

the proper recipient(s) within its jurisdiction, and may also be

responsible for relaying the message.

7-31
Given the two roles for an ADMD, this section describes two

distinct sets of functional requirements for an ADMD. The first

is the relaying requirement that is needed to provide PRMD and

other ADMD interworking. The second is analogous to the PRMD '

support to its customers through the integrated UAs . These are

distinct functional differences. The services provided to the

UAs of an ADMD are independent of the requirement that an ADMD

provide a function for interworking with any type of Management

Domain (MD) . Figure 7,18 illustrates the two roles played by an

ADMD

This section is presented in the form of deviations from the

agreements applicable to PRMD-to-PRMD (section 7.5). Unless

explicitly noted in the remainder of this section, all of the

specifications for PRMD to PRMD apply to PRMD to ADMD and ADMD to

ADMD

7-32
PRMD or ADMD

I PM - UA

/

MTA

N

-P2

-PI

(a)

>

>

ADMD

I PM - UA

MTA

PRMD or ADMD PRMD or ADMD

I PM - UA <-- ... P2 ------------------- -> I PM - UA

MTA MTA

'

PI

I

I

I

PI

(b)

Figure 7.18 An ADMD may (b) or may not (a) serve as a relay

7.6.2 Additional ADMD Functionality

The following defines the additional ADMD specific functionality

required over and above that specified in the PRMD section.

7 , 6 . 2 .Relay Responsibilities of an ADMD

ADMDs will relay all content types (not just P2) unchanged

in the absence of a request for conversion.

7-33
7 . 6 . 2 .

PI Protocol Classification Changes

Table 7.19 describes the changes to the PRMD PI Protocol

classifications required for a delivering Administration

domain (with respect to the original message; this means the

domain which originates the delivery reports)

Table 7.19 PI Protocol Classification Changes for a Delivering ADMD

Protocol Elements Class

Deliveredlnfo

typeOfUA

ReportedRecipientlnfo

SupplementaryInformat ion

GlobalDomainldentifier

PrivateDomainldentifier

H

H See Note 1.

H

For relaying Administration domains, the classifications are all "X"

For originating Administration domains, these are all

"NOT APPLICABLE".

Note 1: Domains providing access to TELEX/TELETEX recipients, whether

directly or indirectly as a result of bilateral agreements

between domains, must ensure that this information, when

present, is accessible by the recipient of the delivery report.

7. 6. 2,0/R Names

0/R Names shall consist of:

o CountryName

,

o AdministrationDomainName

as well as one of the following:

o PrivateDomainName

,

o PersonalName

,

o OrganizationName

,

7-34
o OrganizationalUnit

,

o UniqueUAIdentif ier

,

o X121Address.

and permits the optional inclusion of a

o DomainDef inedAttributeList

Note: The destination PrivateDomainName or OrganizationName

must be present if destined for a PRMD . The ADMD relaying

the message to that destination PRMD requires this element.

7. 6. 2.

PI ADMD Name

Management Domains (MDs) must specify in the ADMD name field

of the 0/R Name StandardAttributeList in PI, the name of the

Administration domain:

o to which the message is being sent (in recipient names)

o from which the message originated (in the originator

name)

7.6.3

Interworking with Integrated UAs

If the message originates at a UA owned by an ADMD, or is

delivered to such a UA, the 0/R Name follows the same Form 1 Variant 1 constraints as the base specifications; except that the

ADMD name is the name of the ADMD that owns the UA and instead of

supplying a PRMD Name, one (or more) of the following must be

provided:

o OrganizationName,

o OrganizationalUnit,

o PersonalName.

and may optionally include a

o DomainDef inedAttributeList

7.6.4 Differences with Other Profiles

7.6.4.

TTC Profile

There are no outstanding issues regarding interworking

between TTC -conformant systems and NBS- conformant systems

with the exception of the number of recipients and the

supported MPDU sizes. The Extensionldentif ier field may

contain a maximum value of 32K-1; however, according to the

current TTC profile, if a message with more than 256

recipients is received, some TTC -conformant domain may

generate a nondelivery notification. This also applies to

7-35
the ReportedRecipientlnfo in a delivery report. Further, a TTC MTA is required to support an MPDU size of at least

32KB. The NBS required MPDU size is 2MB as covered in

section 7. 5. 3. 3. Other differences are shown in Appendix E.

TTC is currently based on Version 4 of the Implementor's

Guide

7. 6. 4.CEPT Profile

See Appendix 7E.

7.6.5 Connection of PRMDs to Multiple ADMDs

Given that Management Domain names (both PRMD and ADMD) shall be

unique within the U.S., then when an ADMD is presented a message

for transfer from a PRMD, it will accept 0/R Names (both

originator and recipient) which have an AdministrationDomainName

field value different than the Administration's name. "Accept"

implies the attempt to route/deliver the message shall be made,

as appropriate , based upon the knowledge that MD names are

unique

Whether this functionality is required by an Administration for

conformance to this agreement is for further study.

If a PRMD is connected to two or more ADMDs which are not

effectively connected (either directly or via a third ADMD) , full

X.400 functionality shall not be available. Problems occur

especially in the areas of:

o Naming,

o Routing,

o Replying.

It should be noted that a single PRMD that is connected to more

than one ADMD can be represented by more than one combination of

country-name, ADMD-name, and PRMD name. For example, it may

occur that the PRMD-name for a particular PRMD may take different

values, depending on the ADMD-name. Implementors should be aware

of the consequences of these possibilities on routing.

7.6.6 Connection of an ADMD to a Routing PRMD

It is possible for a collection of interconnected private domains

to establish one domain as the "gateway" to an ADMD, and hence to

the world.

If an ADMD is connected to such a gateway PRMD, the individual

private domains shall be registered with the Administration.

Administrations need not support such connections.

7-36
Note also that upon receipt by the ADMD of a message originating

somewhere within the PRMD collection, that the Tracelnformation

may contain more than one element.

The X.400 Recommendations specify that an ADMD should not attempt

to relay a message destined for another ADMD through a PRMD, thus

an ADMD should ensure that messages destined for another ADMD are

not relayed through a PRMD. It should be noted, however, that a relaying PRMD will relay any such message it receives.

7.6.7 Management Domain Names

o All Management Domain Names (both Private and

Administration) shall be unique within the U.S.

o A central naming authority shall be established to register

domain names.

7.6.8 Envelope Validation Errors

For validation errors, a non-delivery notice shall be generated

(if possible) with reason code of 'unableToTransfer ' and

diagnostic code of ' invalidParameters ' (unless specified

otherwise)

ADMDs will validate PI Envelopes in the following areas:

a) The X.409 syntax of all elements should be checked.

b) The pragmatic constraint limits (lengths of fields and

number of occurrences of fields) should be checked.

c) Semantic validation of the following elements should be

done

o originator 0/R Name,

o recipient 0/R Name in the Recipientlnfo

,

o Priority.

d) Only recipient Names with the responsibility flag set should

be validated. The validation of 0/R names is defined in

7. 8. 3. 3; the validation of priority is defined in 7. 8. 3. 7.1.

MPDU Identifier Validation

o Validation of the GlobalDomainldentifier component of

the MPDU Identifier is performed upon reception of a message (i.e., as a result of a TRANSFER. Indication)

o The country name should be known to the validating

domain, and depending on the country name, validation

of the ADMD name may also be possible.

7-37
o Additional validation of the GlobalDomainldentifier is

performed against the corresponding first entry in the

Tracelnformation. If inconsistencies are found during

the comparison, a non-delivery notice with the above

defined reason and diagnostic codes is generated.

o A request will be generated to the CCITT for a more

meaningful diagnostic code (such as

1 XnconsistentMPDUXdentifier ' )

7,6.9 QuaXitv of Service

7 . 6 . 9 .Domain AvaiXabilitv

7 . 6 . 9 . 1 .

ADMD AvailabiXitv

The goal is to provide 24 hour per day availability.

Note that there will be periods of time when an ADMD

may be unavailable due to maintenance windows in its

supporting network or in an MTA within the domain.

7 . 6 . 9 . 1 .PRMD Availability

Although the goal of PRMD availability is also 24 hours

per day, business reasons are likely to dictate some

different level of availability. ADMDs shall require a profile from the PRMD that indicates its schedule of

regular availability to the ADMD.

7 . 6 . 9 .

Delivery Times

In the absence of standardized quality of service

parameters, the following are agreed to. When standardized

parameters from CCITT Study Group I become available, they

shall be adopted.

a) In table 7.20 the following delivery time targets are

established:

Table 7.20 Delivery Time Targets

Delivery Class 95% Delivered Before

Urgent 3/4 hour

Normal 4 hours

Non-Urgent 24 hours

b) The interval(s) between retries and the number of retry

7-38
attempts that an ADMD uses in attempting delivery to a PRMD or integrated UA, will be locally determined

domain parameters. However, the total elapsed times

after which delivery attempts will be stopped are shown

in table 7.21. This implies that, after these times, a Non-Delivery Notice will be generated.

An Administration shall continue to attempt delivery until

the forced nondelivery time, even if the recipient domain

has scheduled an unavailability window.

Table 7.21 Forced Nondelivery Times

Delivery Class NonDeliverv Forced After

Urgent 4 hours

Normal 24 hours

Non-Urgent 36 hours

Note: Both tables apply to the period between acceptance by

the originating MTA in the originating Administration domain

to the time of delivery in the destination Administration

domain. Transit time within PRMDs is NOT included in the

above times.

7.6.10 Billing Information

a) All aspects relating to billing, charging, tariffs,

settlement, and in particular to the use of the

billinglnformation field in the delivery report, is subject

to bilateral agreement, and shall not be addressed in these

implementation agreements.

b) No ADMD shall require a PRMD to supply or process billing

information.

7.6.11 Transparency

a) No PI extensions, other than the MOTIS extensions are to be

allowed (Reference A/3211). Should an ADMD receive a message containing PI extensions, it shall generate a

non-delivery notice (if possible) with reason code of

unableToTransfer and diagnostic code of invalidParameters

If MOTIS elements are present, a relaying MTA can optionally:

o Relay the message. If the MTA does relay, it must not

drop any of the protocol elements.

7-39
o Non-Deliver the message.

A receiving MTA can optionally:

o Deliver the message

o Non-Deliver the message.

b) The CCITT has been requested to establish a more meaningful

diagnostic code (such as protocolError) for this occurrence.

c) P2 extensions shall be relayed transparently by ADMDs

7.6.12 RTS Password Management

RTS password management shall be a local matter. This includes:

o password length

o frequency of changes

o exchange of passwords with communicating partners

o loading- passwords ( i.e., the timing of password

changes with respect to active associations).

7.6.13 For Further Study

Issues requiring further study are:

o Intra-Domain Routing

o Multi -Vendor Domains

7.7 INTER and INTRA PRMD CONNECTIONS

7.7.1 Introduction

This section is limited in scope to issues arising from the

indirect connection of a PRMD to another PRMD or to an ADMD, and

to the interconnection of MTAs to form inter-PRMD connections.

Indirect means that the connection is made via a relaying PRMD.

The X.400 Recommendations describe the way that a PRMD connects

to a ADMD and the way that an ADMD connects to another ADMD. The

Recommendations do not, however, describe the way that a PRMD

connects indirectly to an ADMD or another PRMD, nor do they

describe the way that MTAs are connected within a PRMD. These

configurations (shown in Figures 7.22 and 7.23) are useful, for

example, in connecting equipment from different vendors at a single customer site.

The PI protocol and its related services for both inter and intra

PRMD connections are addressed in this section. In addition, a method for routing within a PRMD is given. It is recognized that

uniform methods for Administration, maintenance, and quality of

service should be developed for such configurations, and this

7-40
work is for further study.

This section describes the minimum that must be provided in order

to implement a relaying PRMD and a MTA within a PRMD.

This section is presented in the form of deviations from

agreements applicable to PRMD to PRMD connection (section 7.5).

That is, unless specifically noted in the remainder of this

section, the agreements in section 7.5 apply to both relaying

PRMDs and MTAs within a PRMD.

It should be noted that the comments regarding ORNames in Section

7.6.5 also apply to this section.

7.7.2 The Relaying PRMD

A PRMD that has the capability of relaying messages to another

PRMD is called a relaying PRMD. A PRMD implementation need not

claim to be a relaying PRMD. A PRMD implementation which does

claim to be a relaying PRMD must follow the implementation

agreements in this section.

7 . 7 . 2 .

Relay Responsibilities of a PRMD

The responsibilities of a relaying PRMD are the same as

those of an ADMD (as specified in sections 7.6.8 and

7. 6. 2.1). In addition, the PRMD will simply deliver

messages routed to it from an ADMD, even if this results in

routing a message from the ADMD to the PRMD to another ADMD.

7 . 7 . 2 .Interaction with an ADMD

In order for an ADMD to route a message to ADMD A via ADMD

B, it must know that A is reachable through B. Similarly,

in order for any MD to route a message to PRMD A via a relaying PRMD B, it must know that A is reachable through B

(see Figure 7.24).

Relay

Figure 7.22 Relaying PRMD

7-41
Figure 7.23 Intra PRMD connections

Note 1: Section 7.6.6 specifies that ADMDs are not required to

connect to a relaying PRMD, but they are not precluded from doing

so

Note 2: Tracelnformation may have more than one sequence on

submission of a message by a relaying PRMD to an ADMD.

Figure 7.24 MD C must know of A to route the message

7.7.3 Intra PRMD Connections

A PRMD is composed of MTAs which cooperate to perform the

functions expected of a domain. An MTA implementation need not

claim to follow the implementation agreements of this section.

7 . 7 , 3 .Relay Responsibilities of an MTA

The relaying responsibilities of an MTA are the same as

those of an ADMD (as specified in sections 7.6.8 and

7. 6. 2.1) with one exception: loop suppression within the

domain is done using the MOTIS InternalTracelnfo protocol

element. The MTA must validate the InternalTracelnfo (see

section 7. 8. 3.for details on validation). In addition,

the PRMD will simply deliver messages routed to it from an

ADMD, even if this results in routing a message from the

7-42
ADMD to the PRMD to another ADMD (please see section 7.6.6).

7 . 7 . 3 ,

Loop Suppression within a PRMD

a) The only mechanism define in the X.400 Recommendations

for suppressing loops is Tracelnformation, which is

added on a per domain basis to detect and suppress

loops among domains. Loops among MTAs within a domain

need to be detected and suppressed. This implies that

each MTA must add trace information that is meaningful

within the domain. The MOTIS solution of adding

InternalTracelnfo to the PI Envelope of a message was

adopted. The definition of InternalTracelnfo is given

in table 7.25. The InternalTracelnfo is added by each

MTA within a PRMD to handle a message, and it is

examined in the same way as Tracelnformation to detect

and suppress loops.

InternalTracelnfo : := [APPLICATION 30]

IMPLICIT SEQUENCE OF

SEQUENCE { MTAName

,

MTASuppliedlnfo }

MTAName : := Printable String

Figure 7.25 Definition of InternalTracelnfo

If the MTAName and password of X.411 are used for

validation, then it is recommended that the MTAName

used for validation also be used in the

InternalTracelnfo. However, there is a complication:

in X.411, MTAName is an IA5String, and the MTAname

defined by MOTIS is a PrintableString. Efforts will be

made to change the MOTIS definition from

PrintableString to IA5String.

b) Three actions are defined in MTASuppliedlnfo: relayed,

rerouted, and recipientReassignment as shown in table

7.26. The recipientReassignment action is not

supported in these agreements. The ability to generate

it is not required, and if it is present on an incoming

message, the action field will be ignored.

7-43
MTASuppliedlnfo : := SET { arrival [0] IMPLICIT Time,

deferred [1] IMPLICIT Time OPTIONAL,

action [2] IMPLICIT INTEGER

{ relayed(O) , rerouted(l), recipientReassignment ( 2 ) } previous MTAName OPTIONAL }

Figure 7.26 Defined Actions in MTASuppliedlnfo

7 . 7 . 3 .

Routing Within a PRMD

a) Routing within a PRMD is complicated by the lack of a directory standard. In particular, it constrains

intra-domain routing decisions to be based on some

combination of the intra-domain attributes of the 0/R

Name, Organization Name Organizational Units, and

Personal Name . In order to enhance interworking and to

reduce the difficulty of configuring intra-domain

connections, it is useful to restrict the ways in which

these may be used in making routing decisions.

b) However, it is recognized that vendors may wish to

provide MTAs with varying degrees of routing capabi lity

within a PRMD as a temporary expedient until

appropriate standards for automated construction of

directories and routing tables are available. This

section assigns class numbers to certain levels of

routing capability and discusses the consequences of

using MTAs which fall into each class. The

classification scheme will allow some diversity in

allocating 0/R Name space and in configuring

intra-domain routes.

c) When other methods are recommended by standards bodies,

the classification scheme described here will become

obsolete. Large-scale, multi-vendor PRMDs may not be

practical in the absence of standardized methods.

7 . 7 . 3 . 3 .

Class Designations

When it is clear that a message is to be delivered

within a domain, the Country Name, ADMD Name, and PRMD

Name have already served their purpose in determining

the next MTA in the route to the recipient. The

remaining fields that might be used on making routing

decisions within the PRMD are the Organization Name,

Organizational Units, and Personal Name.

MTAs are classified by their ability to discriminate

between 0/R names when making routing decisions within

a PRMD. Conformant MTAs will be classified as shown in

7-44
table 7.27.

Table 7.27 Conformant MTA Classifications

Class 1 Class 2 Class 3

Organization Name H H H

SEQUENCE OF Organizational Unit X H H

Personal Name X X H

a) An 'H' means that the MTA must be able to base its

intra-domain routing decisions on the given

component of the 0/R Name. In particular, both

Class 2 and Class 3 MTAs must be able to

discriminate on all the members in a supplied

sequence o.f OrganizationalUnits . A Class 3 MTA

must be able to discriminate on all of the

elements in a PersonalName

An 'X' means that the MTA need not have the

ability to discriminate on the given component.

b) There is a hierarchy in support of components.

The ability to discriminate on a given component

does not imply the requirement to do so: e.g., a Class 3 MTA is not required to have tables for

every PersonalName in the domain. Equally, an MTA

which can discriminate on OrganizationalUnits to

make routing decisions need not always use the

full sequence in an 0/R Name if a partial sequence

provides enough information.

c) The above classifications only apply to routing

decisions in selecting a next hop within a domain.

All MTAs are entitled to examine the full 0/R Name

when identifying their own directly served UAs

d) The routing table of a Class 1 MTA will be

relatively small, because intra-domain routing

decisions are based solely on OrganizationName

The routing table of a Class 2 MTA may be

substantially larger and more complex because of

its ability to discriminate on OrganizationalUnits

as well as OrganizationName to make routing

decisions. The routing table of a Class 3 MTA may

be larger still, because its use of the components

of PersonalName in addition to the other

information.

7-45
7 . 7 . 3 . 3 .

Specification of MTA Classes

If an MTA implementation claims to follow the

implementation agreements, it must be either a Class 1,

Class 2 , or a Class 3 MTA. The class of an MTA

implementation should be specified so that PRMD

administrators can choose equipment properly.

7 . 7 . 3 . 3 .

Consequences of Using Certain Classes of MTAs

Definition: An MTA which accepts submission requests

and furnishes delivery indications to a

UA is said to "directly serve" the UA.

a) The presence in a domain of an MTA acting as a

Class 1 or Class 2 MTA imposes administrative

restrictions on the assignment of 0/R Names to UAs

and in the configuration of routes within that

domain.

o A Class 1 MTA may directly serve UAs from

several OrganizationNames . However, if a

Class 1 MTA directly serves a UA with a given

OrganizationName , no other MTA in the domain

may directly serve a user with the same

OrganizationName. This means that if all

MTAs in a domain are Class 1, then all UAs

with a given OrganizationName must be

assigned to the same MTA.

o A Class 2 MTA may directly serve UAs from any

combination of OrganizationName and sequence

of OrganizationalUnits . However, if a Class

2 MTA directly serves a UA with a given

combination, no other MTA in the domain may

directly serve a user with the same

combination. This means that if all MTAs in

a domain are Class 2, then all UAs with a

given OrganizationName and sequence of

OrganizationalUnits must be assigned to the

same MTA.

o A domain consisting entirely of Class 3 MTAs

is free of all the above restrictions.

b) If Class 1 or Class 2 MTAs are used to perform

relaying within a PRMD containing MTAs of other

classes, care must be exercised in determining the

topology of the domain to avoid leaving certain

UAs inacessible from certain MTAs within the

domain. The example below shows one of the

configurations that should be avoided. The

7-46
example is intended to stimulate careful

examination of the relationship between network

and organizational topologies.

Figure 7.28 Example of a confirguration to be avoided

In Figure 7.28, B will route all messages for

Organization X to either A or C because B is a Class 1 MTA. The administrator who created this configuration

probably wanted B to route some messages for

Organization X .to A, and some to C. However, B does

not have the capability for this because it is only a Class 1 MTA. The configuration in Figure 7.28 can be

corrected by replacing B with a Class 2 or Class 3 MTA.

7 . 7 . 3 .Uniqueness of MPDUidentifiers Within a PRMD

When generating an IA5String in an MPDUidentifier , each MTA

in a domain must ensure that the string is unique within the

domain. This shall be done by providing an MTA designator

with a length of 12 octets which is unique within the

domain, to be concatenated to a per message string with

maximum length of 20 octets.

Two pieces of information, the MTA name and MTA designator,

need to be registered within a PRMD to guarantee uniqueness.

This registration facility need not be automated. If the

MTA name is less than or equal to 12 characters, it is

recommended that it also be used as the MTA designator.

7.7.4 Service Elements and Optional User Facilities

A PRMD made up of MTAs which support varying sets of service

elements in addition to those required in these agreements may

appear to provide inconsistent service for these elements. For

example, if one MTA supports deferred delivery and another MTA

does not, then deferred delivery can be used by some, but not

all, users in the PRMD. Similarly, if one MTA supports return of

contents and another does not, then a user outside of the PRMD

will receive returned contents for messages sent to one user, but

not for messages sent to another user. Note that this same

inconsistency occurs when sending to two PRMDs which support

different additional optional elements.

7-47
7.7.5 X.400 Protocol Definitions

This section describes additions and modifications to section

7.5.3 which are required for implementation of a relaying PRMD or

an MTA within a PRMD.

7 . 7 . 5 .

Protocol Classification

a) The classification scheme given in section 7. 5. 3.1

applies to elements passing from one PRMD to another.

For both relaying PRMDs , and MTAs in a PRMD, the same

classification scheme will be used, but within a PRMD

the classification applies to elements passing from one

MTA to another.

b) In addition to the classifications given in section

7. 5. 3.1, a classification of Prohibited has been used.

PROHIBITED = P

This element shall not be used. Presence of this

element is a protocol violation.

7 . 7 . 5 .PI Protocol Elements

Table 7.29 contains protocol elements and their classes. An

* signifies that the classification of the protocol element

has not changed from Table 7.11.

7-48
f

Table 7.29 PI Protocol Elements

Element Class Restrictions and Comments

UMPDUEnvelope

MPDUIdentifier M* This field needs to be unique

within a PRMD. See sections

7. 7. 3.for the method of

ensuring uniqueness.

originator M* It is recommended that all

components of the originator's

CRName be included to help ensure

that reports can be returned.

Trace Informat ion M* The first MTA in the domain to

receive the message adds the

Tracelnformation. Subsequent

MTAs can update the

Tracelnformation in the event of

conversion or deferred delivery.

When a message is generated, the

originating MTA adds the

Tracelnformation.

InternalTracelnfo M/P This element is mandatory for

envelopes transferred between

MTAs within a PRMD, and

prohibited in messages

transferred outside the domain.

Elements are always added to the

end of the sequence. (See Note 1)

InternalTracelnfo

MTAName

M MTANames within a PRMD must be

unique. See section 7. 7. 3.

for

the method of assuring uniqueness

Maximum length = 32 characters.

MTASuppliedlnfo M

(Continued on next page.)

7-49
Table 7.29 PI Protocol Elements, continued

Element Class Restrictions and Comments

MTASuppliedlnfo

arrival M

deferred X This field must be generated by

MTAs which perform deferred

delivery

action M See section 7. 7. 3.

for

restrictions on values of this

field.

previous * X This field must be generated by

MTAs which perform rerouting.

DeliveryReportEnvelope

Trace Information M* The first MTA in the domain to

receive the report adds the

Tracelnformation. When a report

is generated, the originating MTA

adds the Tracelnformation.

InternalTracelnfo

1 M/P

1

This field is mandatory for

envelopes transferred between

MTAs within a PRMD, and

prohibited in messages

transferred outside the domain.

(See Note 1)

Del iveryReportContent

intermediate InternalTracelnfo P If it were possible to include

this field in the delivery report

content, an audit and confirmed

report could be provided to

detect problems within a PRMD.

Efforts are being made to add

this field to the MOTIS

definition.

Deliveredlnfo

typeOFUA R* It is the responsibility of the

MTA generating the report to

generate this element.

(Continued on next page.)

7-50
Table 7.29 PI Protocol Elements, continued

Element Class Restrictions and Comments

ProbeEnvelope

Tracelnformation M* The first MTA in the domain to

receive the probe adds the

Tracelnformation. When a probe

is generated, the originating MTA

adds the Tracelnformation.

InternalTracelnfo

f

M/P This field is mandatory for

envelopes transferred between

MTAs within a PRMD, and

prohibited in messages

transferred outside the domain.

(See Note 1)

Note 1: The M classification is only applicable if an

implementation is claiming conformance according to section

7.10.2, point (g) 4th bullet.

7 . 7 . 5 .

Reliable Transfer Server (RTS)

In the pUserData of PConnect, the value of

applicationProtocol should be 1. This value was chosen

because the agreements on intra-domain connections are not

strictly PI, nor are they MOTIS. Philosophically, it would

be good to choose a new application protocol identifier for

these agreements, but this introduces too many practical

problems. Since these agreements are closer to PI than to

MOTIS, the value of 1 will be used. This will not cause

interworking problems between domains, because the only

deviation from PI is the InternalTracelnfo , which will not

be present in messages transferred outside of a domain.

7.8 ERROR HANDLING

This section describes appropriate actions to be taken upon receipt of

protocol elements which are not supported in this profile, malformed

MPDUs , unrecognized 0/R Name forms, content errors, errors in

reports, and unexpected values for protocol elements.

7-51
7.8.1 MPDU Encoding

The MPDU should have a context-specific tag of 0, 1, or 2. If it

does not have one of these tags, it is not possible to figure out

who originated the message. Therefore, the way this error is

reported is a local matter.

7.8,2 Contents

Once delivery to the UA has occurred, it is not possible to

report errors in P2 information to the originator. In addition,

it seems unreasonable to insist that the MTA that delivers a

message ensure that the P2 content of the message is acceptable.

As a result, the handling of content errors is a local matter.

7.8.3 Envelope

This section describes the handling of errors in message

envelopes. Some of the error conditions described below may be

detected in a recipient's 0/R Name. This may limit the reporting

MTA's ability to generate a nondelivery notification that

accurately reflects the erroneous 0/R Name in the

ReportedRecipientlnfo . This handling of this situation is a local matter.

7 . 8 . 3 .

Pragmatic Constraint Violations

In all cases of pragmatic constraint violation, a nondelivery report should be generated with a ReasonCode of

unableToTransfer , and a DiagnosticCode of

pragmaticConstraintViolation.

7 . 8 . 3 .Protocol Violations

a) If all required protocol elements are not present, a

nondelivery report with a ReasonCode of

unableToTransfer and a DiagnosticCode of

protocolViolation should be generated.

b) If a protocol element is expected to be of one type,

but is encoded as another, then a nondelivery report

with a ReasonCode of unableToTransfer and a DiagnosticCode of invalidParameters should be

generated.

Note: It would be desirable for the CCITT to add a DiagnosticCode of protocolViolation to allow a more

meaningful description of this problem. A request for this

new DiagnosticCode has been submitted.

7-52
7. 8. 3. 3 0/R Names

a) The domain that has responsibility for delivering a message should also have the responsibility to send the

nondelivery notification if the message cannot be

delivered. Therefore, each MTA should only validate

the 0/R Names of recipients with responsibility flags

set to TRUE. In addition, a nondelivery notification

can only be sent if the originator's 0/R Name is valid.

b) If any element in the 0/R Name is unrecognized or if

the CountryName , AdministrationDomainName , and one of

PrivateDomainName and OrganizationName (and, for ADMDs

PersonalName and OrganizationalUnit) are not all

present, then a nondelivery report should be generated

with a ReasonCode of unableToTransfer , and a DiagnosticCode of unrecognizedORName . If the message

can be delivered even though the ORName is invalid,

delivery is a local matter. Note, however, that if the

message is delivered, the invalid ORName might be

propagated through the X.400 system (e.g., by

forwarding)

c) If the 0/R Name has all of the appropriate protocol

elements and the message still cannot be delivered to

the recipient, the following DiagnosticCodes may appear

in the nondelivery report: unrecognizedORName,

amb iguousORName , and uaUnavailable

7 . 8 . 3 .Trace Informat ion

a) Since non- re laying domains need not do loop

suppression, domains with responsibility for delivering

the message need not be concerned about the semantics

of the Tracelnformation, that is, arrival time and

converted EncodedlnformationTypes can be provided to

the UA without inspection by the MTAs of the domain as

long as the Tracelnformation is properly encoded

according to X.409.

b) When a message is accepted for relay, the relaying

domain must check that a Tracelnformation SEQUENCE has

been added by the domain that last handled the message.

If the appropriate Tracelnformation was not added, this

should be treated as a protocolViolation (section

7. 8. 3. 2) .

c) In addition, the relaying domain must check that the

information was added in the sequence defined by the

rules for adding Tracelnformation in the CCITT X.400

Implementor's Guide. If the sequence is invalid, then a nondelivery report should be generated with a

7-53
ReasonCode of unableToTransfer and a diagnosticCode of

invalidParameters

Note: It would be desirable for the CCITT to add a diagnostic code of invalidTracelnformation to allow a more

meaningful description of this problem. A request for this

new diagnostic code will be submitted.

7 . 8 . 3 .InternalTracelnfo

This section applies only to MTAs which follow the

agreements of section 7.7.

a) When a message is accepted for relay from another MTA

in the domain, the relaying MTA must check that an

InternalTracelnfo SEQUENCE has been added by the MTA

that last handled the message. If the appropriate

InternalTracelnfo was not added, this should be treated

as a protocolViolation (section 7. 8. 3. 2).

b) In addition, the relaying MTA must check that the

information was added in the sequence defined by the

rules for adding Tracelnformation in the CCITT X.400

Implementor's Guide. If the sequence is invalid, then

a nondelivery report should be generated with a

ReasonCode of unableToTransfer and a diagnosticCode of

invalidParameters

Note: It would be desirable for the CCITT to add a diagnostic

code of invalidTracelnformation to allow for a more

meaningful description of this problem. A request for this

new diagnostic code will be submitted.

7 . 8 . 3 .Unsupported X.400 Protocol Elements

The protocol elements defined in X.400 but unsupported by

this profile are: the deferredDelivery and

PerDomainBilaterallnfo parameters of the UMPDUEnvelope , the

ExplicitConversion parameter of Recipientlnfo , and the

alternateRecipientAllowed and contentReturnRequest bits of

the PerMessageFlag. Appropriate actions are described below

for domains that do not support the protocol elements.

7 . 8 . 3 . 6 .deferredDelivery

The delivering domain shall do one of the following:

o deliver at once,

o hold for deferred delivery,

o return a nondelivery notification with a

ReasonCode of unableToTransfer and a DiagnosticCode of nOBilateralAgreement

7-54
7 . 8 . 3 . 6 .

PerDomainBi lateral Info

If a delivering domain receives this element, the

element can be ignored.

7 . 8 . 3 . 6 .

ExplicitConversion

If ExplicitConversion is requested the message should

be delivered if possible. That is, if the UA is

registered to accept the EncodedlnformationTypes of the

message, then the message should be delivered even

though the requested conversion could not be performed

along the route. If delivery is not possible, then a

nondelivery report should be generated with a

ReasonCode of conversionNotPerformed with no

DiagnosticCode

7 . 8 . 3 . 6 .

alternateRec ip ientAl lowed

If a delivering domain receives this element the

element can be ignored.

7 . 8 . 3 . 6 .

contentReturnRequest

If a delivering domain receives this element, the

element can be ignored.

7 . 8 . 3 .Unexpected Values for INTEGER Protocol Elements

There are three INTEGERS in the PI Envelope. Appropriate

actions are described below for domains receiving unexpected

values for Priority, ExplicitConversion, and ContentType

7 . 8 . 3 . 7 .

Priority

Additional values for Priority have been suggested by

at least one group of implementors as upward compatible

changes to the X.400 Recommendations. Therefore, if a PRMD receives an unexpected value for Priority, and

this value is greater than one byte in length, a

nondelivery report should be generated with a

ReasonCode of unableToTransfer and DiagnosticCode of

invalidParameters . If the value is less than or equal

to one byte, the PRMD can either generate a nondelivery

report as previously specified or interpret the

Priority as normal and deliver or relay the message.

7-55
7 . 8 . 3 . 7 .

ExplicitConversion

When an unexpected value is received for

ExplicitConversion, it should be handled as in section

7. 8. 3. 6. 3.

7 . 8 . 3 . 7 .

ContentTvpe

If the ContentType is not supported by the delivering

MTA, then a nondelivery report should be generated with

a ReasonCode of unableToTransfer , and a DiagnosticCode

of contentTypeNotSupported.

7 . 8 . 3 .Additional Elements

In the absence of multilateral agreements to the contrary,

receipt of privately tagged elements and protocol elements

in addition to those defined in X.400 will result in a

nondelivery report with a ReasonCode of unableToTransfer and

a DiagnosticCode of invalidParameters

The exceptions to this are the MOTIS elements. The

treatment of MPDU's containing these MOTIS extensions is

described in Section 7.6.11.

7.8.4 Reports

There is no mechanism for returning a delivery or status report

due to errors in the report itself. Therefore the handling of

errors in reports is a local matter.

7.9 MHS USE OF DIRECTORY SERVICES

7,9.1 Directory Service Elements

a) Recommendation X.400 recognizes the need of MHS users for a number of directory service elements. Directory service

elements are intended to assist users and their UAs in

obtaining information to be used in submitting messages for

delivery by the MTS. The MTS may also use directory service

elements to obtain information to be used in routing

messages. Some functional requirements of directories have

been identified and are listed below.

o Verify the existence of an 0/R name.

o Return the 0/R address that corresponds to the 0/R name

presented.

o Determine whether the 0/R name presented denotes a user

or a distribution list.

7-56
o Return a list of the members of a distribution list.

o When given a partial name, return a list of 0/R name

possibilities

o Allow users to scan directory entries.

o Allow users to scan directory entries selectively.

o Return the capabilities of the entity referred to by

the 0/R name

o Provide maintenance functions to keep the directory

up-to-date

b) In addition to functionality, a number of operational

aspects must be considered. These include

user-friendliness, flexibility, availability, expandability,

and reliability.

c) Currently, these aspects of directory service elements and

procedures are under study by both the CCITT and the ISO.

Both organizations are committed to the development of a

single Directory Service specification for use by MHS and

all other OSI based applications.

Given the incomplete nature of the ongoing activities within

the CCITT and the ISO, no implementation details will be

provided now for MHS use of Directory Services . Implementation agreements for MHS Use of Directory Services

will be issued when current activities within the CCITT and

the ISO are stable.

7.9.2 Use of Names and Addresses

a) It is recognized that these agreements enable a wide variety

of naming and addressing attributes (see section 7. 5. 3.

ORName Protocol Elements) wherein each PRMD may adopt

particular routing schemes within its domain.

b) With the exception of the intra-domain connection

agreements:

These agreements make no attempt to recommend a standard

practice for electronic mail addressing.

c) Inter-PRMD addressing may be secured according to practices

outside the scope of these agreements, such as:

o manual directories

o on-line directories

o ORName address specifications

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o ORName address translation.

d) Further, each PRMD may adopt naming and addressing schemes

wherein the user view may take a form entirely different

from the attributes reflected in table 7.12. And, each PRMD

may have one user view for the originator form and another

for the recipient form, and perhaps other forms of user

addressing. In some cases (e.g., receipt notification)

these user forms must be preserved within the constraints of

these implementation agreements. However, mapping between

one PRMD user form to another PRMD user form, via the X.400

ORName attributes of these agreements, is outside the scope

of these agreements

7.10 CONFORMANCE

7.10.1 Introduction

In order to ensure that products conform to these implementation

agreements, it is necessary to define the types and degrees of

conformance testing that products must pass before they may be

classified as conformant . This section defines the conformance

requirements and provides guidelines for the interpretation of

the results from this type of testing.

This section is incomplete and will be enhanced in future

versions of this Agreement. Later versions will reflect the

problems of conformance testing and will outline specific

practices and recommendations to aid the development of

conformance tests and procedures.

7.10.2 Definition of Conformance

For this section, the term conformance is defined by the

following

a) The tests indicated for this section are intended to

establish a high degree of confidence in a statement that

the implementation under test (IUT) conforms (or does not

conform) to the agreements of this section.

b) Conformance to a service element means that the information

associated with the service element is made accessible to

the user (person or process) whenever this agreement says

that this information should be available.

Accessible means that information must be provided

describing how a user (person or process):

o causes appropriate information to be displayed, or

o causes appropriate information to be obtained.

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c) Conformance to PI, P2 , and RTS as part of an X.400 OSI

application requires that only the external behavior of that

OSI system adheres to the relevant protocol standards.

In order to achieve conformance to this section, it is not

required that the inter- layer interfaces be available for

testing purposes.

d) Conformance to the protocols requires:

o that MPDUs correspond to instances of syntactically

correct data units,

o MPDUs in which the data present in the fields and the

presence (or absence) of those fields is valid in type

and semantics as defined in X.400, as qualified by this

profile

,

o correct sequences of protocol data units in responses

(resulting from protocol procedures)

e) Statements regarding the conformance of any one

implementation to this profile are not complete unless a

Protocol Implementation Conformance Statement (PICS) is

supplied.

f) The term "Implementation Under Test" (IUT) is

interchangeable with the term "system" in the definition of

conformance . and may refer to:

o a domain, which may be one or more MTA's with

co- located or remote UA's,

o a single instance of an MTA and co- located UA with

X.400 (PI, P2 , RTS and session) software,

o a relaying product with PI, RTS and session software,

o a gateway product.

g) Claiming Implementation Conformance

o An implementation which claims to be conformant as an

ADMD must adhere to the agreements in sections 7.5 and

7.6.

o An implementation which claims to be conformant as a

PRMD must adhere to the agreements in section 7.5.

o An implementation which claims to be conformant as a

relaying PRMD must adhere to the agreements in section

7.5 and the appropriate sections of 7.7.

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o An implementation which claims to be conformant to the

intra-domain connection agreements must adhere to the

agreements in section 7.5 and the appropriate sections

of 7.7.

7.10.3 Conformance Requirements

7.10.3.1 Introduction

Conformance to this specification requires that all the

services listed as supported in sections 7.5, 7.6, and if

appropriate, 7.7 of these agreements are supported in the

manner defined, in either the CCITT X.400 Recommendations or

these agreements

It is the intention to adopt, where and when appropriate the

testing methodology and/or the abstract test scenarios

currently being defined by the CCITT X.400 Conformance

Group. However, it is recognized that formal CCITT

Recommendations relating to X.400 Conformance Testing will

not be available until 1988. It is also recognized that

aspects of these agreements are outside the scope of the

CCITT, and that other organizations will have to provide

conformance tests in these cases.

7.10.3.2 Initial Conformance

This section is intended to provide guidelines to vendors

who envisage having X.400 products available prior to any

formal mechanism, or "Conformance Test Center" being made

accessible that would allow for conformance to this product

specification to be tested.

It is feasible that vendors and carriers will want to enter

bilateral test agreements that will allow for initial trials

to be carried out for the purposes of testing initial

interworking capabilities. It is equally feasible that for

the purposes of testing interoperability, only a subset of

this specification will initially be tested.

Note: By claiming conformance to this subset of information

the vendor or carrier CANNOT claim conformance to this

entire specification.

There are two aspects to the requirements, interworking and

service, as described in the following sections.

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7.10.3.2.1 Interworking

The interworking requirements for conformance implies

that tests be done to check for the syntax and

semantics of protocol data elements for a system as

defined by the classification scheme of sections

7. 5. 2. 1.1 and 7. 7. 5. 2. For a relay system, the correct

protocol elements should be relayed as appropriate.

For a recipient system, a message with correct protocol

elements must not be rejected where appropriate.

7.10.3.2.2 Service

For information available to the recipients via the

IPMessage Heading and Body, the following should be

made accessible:

o IPMessage ID - only the PrintableString portion of

the IPMessageld needs to be accessible,

o subject,

o primaryRecipients

,

o copyRecipients

,

o blindcopyRecipients

,

o authorizingUsers

,

o originator,

o inReplyTo,

o replyToUsers

,

o importance

,

o sensitivity,

o IA5Text Bodypart.

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7.11 APPENDIX A: INTERPRETATION OF X.400 SERVICE ELEMENTS

The work on service element definitions is limited to those that are

defined as 'supported' in section 7.5 of this specification. Furthermore

it is not the intent of this section to define how information should be

made available or presented to a MHS user, nor is it intended to define

how individual vendors should design their products. In addition,

statements on conformance to a specific service element and the

allocation of error codes that are generated as a result of violations of

the service should be defined in the sections on conformance and errors

as part of the main product specification. The main objective is to

provide clarification, where required, on the functions of a service

element, and in particular what the original intent of the

Recommendations were.

SERVICE ELEMENTS

The following Service Elements defined in X.400 have been examined and

require further text to be added to their definitions to represent the

proposed implementation of these service elements by the X.400 SIG,

The service element clarifications are to be taken in the context of this

profile

Service elements not referenced in this section are as defined in X.400.

PROBE

A PRMD need not generate probes.

If a probe is addressed to and received by a PRMD, the PRMD must respond

with a Delivery Report as appropriate at the time the probe was

processed.

DEFERRED DELIVERY

In the absence of bilateral agreements to the contrary, Deferred Delivery

and Deferred Delivery Cancellation are local matters (i.e., confined to

the originating domain) and need not be provided.

The extension of Deferred Delivery beyond the boundaries of the

initiating domain is via bilateral agreement as specified in Section

3.4. 2.1 of X.411.

Content Type Indication

It is required that both an originating and recipient domain be able to

support P2 content type. The ability for domains to be able to exchange

content types other than P2 will depend on the existence of bilateral or

multi-lateral agreements.

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Original Encoded Information Types Indication

It is required that both an originating and recipient domain be able to

support IA5 text. Support for other encoded information types, for the

purposes of message transfer between domains, will depend on the

existence of bilateral or multi-lateral agreements.

The use of the 'unspecified' form of encoded information type should only

be used when the UMPDU content represents an SR-UAPDU or contains an

auto- forwarded IM-UAPDU.

The original encoded information type of a message is not meaningful

unless a message is converted en route to the recipient. These

agreements support only IA5 text, which should not undergo conversion.

The original encoded information types should be made accessible to the

recipient for upward compatibility with the use of non-IA5 text message

body parts

Registered Encoded Information Types

A UMPDU with an 'unspecified' value for Original Encoded Information Type

shall be delivered to the UA.

Delivery Notification

The UAContentID may be used by the recipient of the delivery notification

for correlation purposes.

Disclosure of Other Recipients

This service is not made available by originating MTAE's to UAE's, but

must be supported by relaying and recipient MTAE's.

By supporting the disclosure of other recipients the message recipient

can be informed of the 0/R names of the other recipient(s) of the

message, as defined in the PI envelope, in addition to the 0/R

Descriptors within the P2 header.

These agreements do not support initiation of disclosure of other

recipients, but the information associated with it should be made

accessible to the recipient for upward compatibility with support for the

initiation of this service element.

Typed Body

As defined in X.400 with the addition of the Private Body Types that are

to be supported. At present there is no mechanism provided within X.420

that would allow you to respond to reception of an unsupported body type.

Action taken in this situation is a local matter.

7-63
Blind Copy Recipient Indication

It should be considered that the recipient's UA acts on behalf of the

recipient, and therefore may choose to disclose all BCC recipients to

each other. Therefore it is the responsibility of the originating domain

to submit two or more messages, depending on whether or not each BCC

should be disclosed to each other BCC.

Auto Forwarded Indication

A UA may choose not to forward a message that was previously

auto -forwarded. In addition there is no requirement for an IPM UA that

does not support non-receipt or receipt notification to respond with a non-receipt notification when a message is auto -forwarded.

Primary and Copy Recipients Indication

It is required that at least one primary recipient be specified; however,

for a forwarded message this need not be present. The recipient UA

should be prepared to accept no primary and copy recipients to enable

future interworking with Teletex, Fax, etc.

Sensitivity Indication

A message originator should make no assumptions as to the semantic

interpretation by the recipients UA regarding classifications of

sensitivity. For example, a personal message may be printed on a shared

printer

Reply Request Indication

In requesting this service an originator may additionally supply a date

by which the reply should be sent and a list of the intended recipients

of the reply. If no such list is provided then the initiator of the reply

sends the reply to the originator of the message and any recipients the

reply initiator wishes to include. The replytoUsers and the replyBy date

may be specified without any explicit reply being requested. This may be

interpreted by the recipient as an implicit reply request. Note that for

an auto -forwarded message an explicit or implicit reply request may not

be meaningful.

Body Part Encryption

The original encoded information type indication includes the encoded

information type(s) of message body parts prior to encryption by the

originating domain. The ability for the recipient domain to decode an

encrypted body part is a local matter. Successful use of this facility

can only be guaranteed if there exists bilateral agreements to support

the exchange of encrypted body parts.

7-64
Forwarded IP message Indication

The following use of the original encoded information type in the context

of forwarded messages is clarified:

o If forwarding a private message body part the originator of the

forwarded message shall set the original encoded information

types in the PI envelope to undefined for that body part.

o The encoded information types of the message being forwarded

should be reflected in the new original encoded information types

being generated.

o See Appendix 7B on recommended practices for the use of the

delivery information as part of Forwarded IP-message.

Multipart Body

It is the intent of multipart bodies to allow for the useful and

meaningful structuring of a message that is constructed using differing

body part types. For example, it is not recommended that a message made

up of only IA5 text should be represented as a number of IA5 body parts,

each one representing a paragraph of text.

7-65
7.12 APPENDIX B: RECOMMENDED X.400 PRACTICES

7.12.1 RECOMMENDED PRACTICES IN P2

1 . ORDescriptor

Vendors following the NBS/OSI Workshop guidelines shall,

whenever possible, generate the ORName portion of an

ORDescriptor in ALL IPM heading fields.

2. ForwardedIPMessage BodyParts

ForwardedIPMessage BodyParts should be nested no deeper than

eight. There is no restriction on the number of

ForwardedIPMessage BodyParts at any given depth.

3. Deliverylnformation

It is strongly recommended that Deliverylnformation be

supplied in both forwarded and autoforwarded message body

parts. Deliverylnformation is useful when a message has

multiple forwarded message body parts because without it,

the EncodedlnformationType(s) of the component forwarded

messages cannot be deduced easily. Deliverylnformation is

useful for autoforwarded messages because the

EncodedlnformationType of an autoforwarded message is

’’unspecified” and the EncodedlnformationType (s) of the

message cannot be determined easily without it. Absence of

the EncodedlnformationType (s) makes it difficult for a UA to

easily determine whether the message can be rendered.

7.12.2 RECOMMENDED PRACTICES IN RTS

1. In the case where S-U-ABORT indicates a temporaryProblem,

reestablishment of the session should not be attempted for a "sensible" time period (typically not less than five

'minutes)

In instances where this delay is not required or necessary,

report a localSystemProblem.

2. S-U- EXCEPTION -REPORT reason codes can be interpreted as

follows

o receiving ability jeopardized (value 1)

Possible meaning: The receiving RTS knows of an

impending system shutdown.

o local ss-User error (value 5)

Possible meaning: The receiving RTS needs to

resynchronize the session dialogue.

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o irrecoverable procedure error (value 6)

Possible meaning: The receiving RTS has had to delete

a partially received APDU, even though some minor

synchronization points have been confirmed.

o non specific error (value 0)

Possible meaning: The receiving RTS cannot handle the

APDU (for example, because it was too large) and wishes

to inform the sending RTS not to try again.

o sequence error (value 3)

Possible meaning: The S -ACTIVITY-RESUME request

specified a minor synchronization point serial number

which does not match the checkpoint data.

3. For purposes of identifying an MTA during an RTS Open, OSI

addressing information should be used. This addressing

information is conveyed by lower layer protocols and is

reflected by the calling and called SSAP parameters of the

S-CONNECT primitives.

MTA validation and identification are related, but separate,

functions. The mTAName and password protocol elements of

the RTS user data should be used for validation, rather that

identification, of an MTA. The RTS initiator and responder

may independently require each other to supply mTAName and

password.

The CallingSSUserReference parameter of the S-CONNECT

primitives should only have meaning to the entity that

encoded it and should not be used to identify an MTA.

7.12.3 RECOMMENDED PRACTICES FOR ORName

Table 7.12 stipulates that the StandardAttribute^ist must contain

either PrivateDomainName or OrganizationName . It is recommended

that, for both originator and recipients in a private domain, the

PrivateDomainName field be used.

It is recommended that there should be a DomainDefinedAttribute

to be used in addressing UAs in existing mail systems, in order

to curtail the proliferation of different types of

DomainDefinedAttributes used for the same purpose. The syntax of

this DomainDefinedAttribute conforms to the CCITT Pragmatic

Constraints, and thus has a maximum value length of 128 octets

and a type length of 8 octets, each of type Printable String.

Only one occurrence is allowed.

This DomainDefinedAttribute has the type name "ID" (in

uppercase) . It contains the unique identifier of the UA used in

addressing within the domain. This DomainDefinedAttribute is to

7-67
be exclusively used for routing within the destination domain

(i.e., once routed to that domain via the mandatory components of

the StandardAttributeList) ; any other components of the

StandardAttributeList may be provided. If they conflict delivery

is not made.

The contents of this parameter need not be validated in the

originating domain or any relaying domain, but simply transferred

intact to the next MTA or domain.

Class 2 and class 3 MTAs in a PRMD should allow administrators to

decide the number of OrganizationalUnits that should appear in

user names, instead of imposing a software controlled limit which

is less than four. This is desirable because when two different

vendors impose different limits on the number of

OrganizationalUnits in a name, it becomes difficult for the

administrator to choose a sensible naming scheme.

There are existing mail systems that include a small set of nonPrintable String characters in their identifiers. For these

systems to communicate with X.400 messaging systems, either for

pass-through service or delivery to X.400 users, gateways will be

employed to encode these special characters into a sequence of

Printable String characters. This conversion should be

performed by the gateway according to a common scheme and before

insertion in the ID DDA, which is intended to carry electronic

mail identifiers. X.400 User Agents may also wish to perform

such conversions.

It is recommended that the following symmetrical encoding and

decoding algorithm for non-Printable String characters be

employed by gateways. The encoding algorithm maps an ID from an

ASCII representation to a PrintableString representation. Any

non-printable string characters not specified in the table are

covered by the category "other" in the table below.

7-68
The principal conversion table for the mapping is as follows:

Table 7B.1 Printable string to ASCII mapping

ASCII Character Printable String Character

% (percent) (P)

@ (at sign) (a)

! (exclamation) (b)

" (quote mark) (q)

(underline) (u)

(

( left paren.

)

(1)

) (right paren.) (r)

other ( 3DIGIT)

where 3DIGIT has the range 000 to 377 and is interpreted as the octal

encoding of an ASCII character.

To encode an ASCII representation to a PrintableString, the table and the

following algorithm should be used:

IF current character is in the encoding set THEN

encode the character according to the table above

ELSE

write the current character;

continue reading;

To decode a PrintableString representation to an ASCII representation,

the table and the following algorithm should be used:

IF current character is not "(" THEN

write character

ELSE

{look ahead appropriate characters;

IF composite characters are in the above table THEN

decode per above table

ELSE

write current character;

} continue reading;

Class 2 and class 3 MTAs in a PRMD should allow administrators to

decide the number of OrganizationalUnits that should appear in

user names, instead of imposing a software controlled limit which

is less than four. This is desirable because when two different

vendors impose different limits on the number of

OrganizationalUnits in a name, it becomes difficult for the

administrator to choose a sensible naming scheme.

7-69
7.12.4 POSTAL ADDRESSING

For domains wishing to support postal (or physical) delivery

options, the following interim set of "nationally-defined" domain

defined attributes are recommended. The CCITT will define

Standard Attributes in support of physical delivery in its 1988

Recommendations; this is only an interim solution.

CCITT will also be addressing the services associated with

physical delivery. This interim solution does not address the

end-to-end service aspects of physical delivery; in particular,

the following IPM service elements do not currently extend

outside of the X.400 environment:

o alternate Recipient Assignment

o PROBE

o Receipt Notification / Non-Receipt Notifications

o Grade of delivery

"Delivery" means passing a message from the MTS to the physical

delivery system (PDS), and not to the user (or user agent).

The following three DDAs are recommended to be used to specify a postal (or physical) address:

CNTRPC - encodes the country and postal code for postal

delivery. The DDA value is of the form

"Country?Postalcode" (for example, "USA722096" ) . The

country field is optional, the postal code is optional;

the separator ("?") is not. If both country and postal

code are missing, this DDA should not be specified.

PDA 1 - The country and postal code fields are free- form text.

PDA 2 - These two DDA (signifying Postal Delivery Address

strings 1 and 2) form a 256 character free-form postal

address. Fields are separated by a question mark

("?"). There is no implied separator between PDAl and

PDA2 . The meaning of the fields are defined by each

domain supporting the physical delivery interface.

PDAl contains the first 128 characters, PDA2 the next

128 characters. If the PDA string is less than 128

characters, PDA2 is not used.

7-70
For example, if the domain interprets the PDA fields as lines,

the address

Mr. John Smith

Conway Steel

123 Main Street

Reston VA 22096

would be encoded as follows:

type = "PDA1" value = "Mr. John Smith?Conway Steel?123 Main

Street?Reston VA"

CNTRPC = "722096"

7.12.5 EDI use of X.400

7.12.5.1 Introduction and Scope

This is a guideline for EDI data transfer in an X.400

environment conforming to the NBS agreements. These

recommended practices outline procedures for use in

transferring EDI transactions between trading partner

applications in an attempt to facilitate actual X.400

implementation by EDI users.

The scope of this guideline is to describe specific

recommendations for adopting X.400 as the data transfer

mechanism between EDI applications.

7.12.5.2 Model

The MHS recommendations can accommodate EDI through the

approach illustrated below. Many Message Transfer (MT)

service elements defined in the X.400 recommendations are

particularly useful to the EDI application.

7-71
X.400 Message (1 EDI interchange)

Envelope

Content

MHS Message

> PI Control

Information

>

One

EDI

Interchange

This diagram depicts an EDI content (1 EDI interchange)

enveloped by the PI MHS envelope. All the MT Services

defined in the X.400 Recommendations may be used for EDI.

However, it is not required to support optional or nonessential services to exchange EDI data between EDI users.

When an EDI user submits an EDI Trade Document to the EDI

User Agent, the EDI UA will submit the EDI content plus PI

envelope to the Message Transfer System (MTS)

EDI EDI

MTS y' . __ \ UA / \ N / N X User

•

The EDI UA must support the essential MT Services as defined

in these Agreements; for example, as a minimum, to provide

default values for services not elected by the EDI user,

such as Grade of Delivery.

Note: MT Services are not necessarily made available by the

EDI UA to the EDI user.

7-72
7.12.5.3 Protocol Elements Supported for EDI

The following PI protocol elements will be used to support

EDI applications:

Content Type

For EDI applications, the content type will be 0

(undefined content)

Original Encoded Information Types

Any EIT defined in the X.400 Recommendations may be

used to specify the encoding of EDI content. However,

for ASC X12 EDI applications in particular, it is

expected that the "undefined" and "IaSText" EIT's will

normally be used, with "undefined" used to signify the

EBCDIC character set.

7.12.5.4 Addressing and Routing

It is anticipated that connection of some existing systems

to an X.400 service for EDI purposes will be by other than

X.400 protocols, at least in the short term.

EDI messages entering the X.400 environment will therefore

need to have X.400 0/R Names added to identify the

origination and recipient trading partners, typically by

means of local directory services in the origination domain

which will map EDI identifiers/addresses into 0/R Names.

Such 0/R Names will contain Standard Attributes as defined

in Table 7.12 and for recipient trading partners will at

least identify the destination domain.

In the case of trading partners outside the X.400

environment, it is expected, however, that there will be

cases where message delivery will require the provision of

addressing information beyond that which can be carried in

Standard Attributes. In such cases, Domain Defined

Attributes are recommended to be used.

The syntax of this DDA is as defined in Table 7.12, with a single occurrence having the type name "EDI” (uppercase) and

a value containing the identifier/address of the trading

partner. For ASC X12 purposes, specifically, this value

will comprise the 2 digit interchange ID qualifier followed

by the interchange ID (max 15 characters) . Routing on this

DDA shall only occur, if at all, in the destination domain.

7-73
7.13 APPENDIX C: RENDITION OF IA5Text AND T61String CHARACTERS

7.13.1 GENERATING AND IMAGING IA5Text

The characters that may be used in an IA5String are the graphic

characters (including Space), control characters and Delete of

the IA5 character repertoire ISO 646.

The graphic characters that may be used with a guaranteed

rendition are those related with positions 2/0 to 2/2, 2/5 to

3/15, 4/1 to 5/10, 5/15 and 6/1 to 7/10 in the basic 7-bit code

table

The other graphic characters may be used but have no guaranteed

rendition.

The control characters that may be used but have no guaranteed

effect are a subset consisting of the format effectors 0/10 (LF)

,

0/12 (FF) and 0/13 (CR) provided they are used in one of the

following combinations:

CR LF to start a new line

CR FF to start a new page (and line)

LF .

.

' LF to show empty lines (always after one of the

preceding combinations)

The other control characters or the above control characters in

different combinations may be used but have no guaranteed effect.

The character Delete may occur but has no guaranteed effect. The

lASString in a P2 IA5Text BodyPart represents a series of lines

which may be divided into pages. Each line should contain from 0

to 80 graphic characters for guaranteed rendition. Longer lines

may be arbitrarily broken for rendition. Note that X.408 states

that for conversion from IA5Text to Teletex, the maximum line

length is 77 characters.

7.13.2 GENERATING AND IMAGING T6 IS trine

For further study.

7-74
7.14 APPENDIX D: DIFFERENCES IN INTERPRETATION DISCOVERED THROUGH

TESTING OF THE MHS FOR THE CeBit 87 DEMONSTRATION

Several interworking problems were discovered through multi-vendor

testing. These problems, and recommendations for solutions to them are

discussed in this appendix.

7.14.1 ENCODING OF RTS USER DATA

The password is defined as an ANY in the X.400 Recommendations,

and implementor's groups have decided to use an IA5String for

this field. There was some confusion about what the X.409

encoding for this IA5String would be, and the correct encoding

is :

class: context specific

form: constructor

id code: 1 length: length of contents

contents: (primitive encoding)

IA5String

length:

contents

16

length of contents

the password string

class: context specific

form: constructor

id code: 1 length: length of contents

contents: (constructor encoding) left as an exercise for the

reader

Implementations should be prepared to receive any X.409 type for

the password because of its definition as an ANY.

7.14.2 EXTRA SESSION FUNCTIONAL UNITS

One vendor proposed more than the required set of functional

units on opening the session connection, and the receiver

rejected the connection. All debate aside about whether the

initiator should have proposed units outside of the required set,

or whether the receiver should have rejected the connection, the

set of functional units can be negotiated in a straightforward

way. The following is recommended.

If the initiator proposes using more than the required set of

functional units, the responder should specify the set of

functional units that it would like to use (which should include

the required set) in the open response. The session

implementations will automatically use the intersection of the

units proposed by both sides.

If the initiator proposes using less than the required set of

functional units, the responder should reject the connection.

7-75
Unfortunately, there is not an appropriate RefuseReason for

rejecting the connection, so instead of refusing the connection

in the response to the S -CONNECT , the receiver should issue an SU-ABORT with an AbortReason of protocolError . Note that it is

valid to issue an S-U- ABORT instead of responding to the SCONNECT. A problem report has been submitted to the CCITT

requesting the addition of a RefuseReason for this situation.

If the responder proposes using less than the required set of

functional units, the session connection is established before

the initiator can check for this. If too few functional units

have been proposed, the initiator should abort the connection

using S-U-ABORT, with an abort reason of protocolError.

7,14.3

MIXED CASE IN THE MTA NAME

The MTA name is frequently exchanged over the telephone when two

systems are being configured to communicate with one another. In

one such telephone exchange, the casing of the MTA name was not

specified, the MTA name consisted of both upper and lower case

letters, and one of the implementations compared MTA names for

equality in a case sensitive manner. Consequently, connections

failed until the problem was detected and repaired. It is

recommended that the MTA name be compared for equality in a case

insensitive manner, and that the password be compared for

equality in a case sensitive manner.

7,14.4

X. 410 ACTIVITY IDENTIFIER

The X.400 Implementor's Guide recommends that the activity

identifier be X.409 encoded, but this is only a recommendation

and not a requirement. Consequently, receiving systems cannot

assume that the activity identifier will be X.409 encoded.

7.14.5

ENCODING OF PER RECIPIENT FLAG AND PER MESSAGE FLAG

In the definition of the PerRecipientFlag in X.411, there is a statement that the last three bits are reserved, and should be

set to zero. It is unclear whether those bits are unused in the

X.409 encoding. Receivers should accept encodings with either

zero or three unused bits. A problem report has been submitted

to the CCITT asking for clarification.

Though there is not any statement in X.411 about the last four

bits of the PerMessageFlag, some vendors have encoded this with

zero unused bits, and some have encoded it with four unused bits.

The PerMessageFlag should be encoded with at least four unused

bits

7-76
7.14.6 ENCODING OF EMPTY BITSTRINGS

There are three valid encodings for an empty bitstring: a constructor of length zero, a constructor of indefinite length

followed by the end-of-contents terminator, and a primitive of

length one with a zero octet as the value.

7.14.7 ADDITIONAL OCTETS FOR BITSTRINGS

Nothing in X.409 constrains an implementation from sending two,

three, four, or even more octets for a bitstring that fits into

one octet, with the undefined bits set to zero. Note that the

number of excess octets is bounded by the pragmatic constraints

guidelines of the CCITT X.400 Implementor's Guide for all of the

bitstrings in PI

7.14.8 APPLICATION PROTOCOL IDENTIFIER

If a value other that 1 is received in the applicationProtocol of

the pUserData in the PConnect, NBS implementations will reject

the connection. If CEN/CENELEC implementations receive a value

other than 8883 for this field, they will reject the connection.

This is an unfortunate state of affairs, because if NBS

implementations accept the value of 8883 without supporting the

MOTIS service elements, they would be misrepresenting themselves.

To make matters worse, CEPT uses a value of 1, but relays MOTIS

elements, which means that MOTIS elements will be relayed to

implementations using a value of 1 to demonstrate that they do

not support MOTIS. Work is continuing to try to find a solution

that will allow European implementations to interwork with U.S

implementations

7.14,9

INITIAL SERIAL NUMBER IN S -CONNECT

Note: Text will be supplied in July 1987.

7.14,10

CONNECTION DATA ON RTS RECOVERY

It is clarified that the ConnectionData is identical in both the

S -CONNECT . request and the S -CONNECT . response . The value of the

ConnectionData is the old Session Connection Identifier.

7,14,11

ACTIVITY RESUME

If an activity is being resumed on a new session connection, it

is not clear from X.410 and X.225 whether all four of the calledss-user reference, the calling-ss-user reference, the common

reference, and the additional reference information should be

specified in the S -ACTIVITY-RESUME , or whether one of the ssuser-references should be absent. It is also unclear whether the

called-ss-user reference should be identical to the calling-ssuser reference if both are present. Consequently, receivers

7-77
should be tolerant of this situation. Appropriate problem

reports will be submitted to the CCITT asking for clarification.

7.14.12 OLD ACTIVITY IDENTIFIER

The Old Activity Identifier in S -ACTIVITY-RESUME refers to the

original activity identifier.

7.14,13 NEGOTIATION DOWN TO TRANSPORT CLASS 0

For European implementations, X.410 specifies that class 0

transport must be supported. However, it is permissible for an

initiator to propose a higher class as the preferred class,

provided that class 0 appears as the alternate class in the TConnect PDU. A responding implementation can choose to use

either the preferred or alternate class, but again, must be able

to use class 0. In other words, for private to private

connections in Europe, class 0 transport is required.

This conflicts with the NBS agreements, since class 0 is only

required if one of the partners in a connection is an ADMD.

7-78
7.15 APPENDIX E: WORLDWIDE X. 400 CONFORMANCE PROFILE MATRIX

Y CONFORMANCE (E)

implies a conformance problem for European products in the U.S.

Y CONFORMANCE (US)

implies a conformance problem for U.S. products in Europe.

o The A/311 profile is specified in Env 41 202, the A/3211 profile

in Env 41 201

o No TTC protocol classification for RTS exists.

o The notation X/Y indicates "X" for PRMDs and "Y" for ADMDs, i.e.

"M/G" would be Mandatory for PRMDs and Generatable for ADMDs.

7-79
Table 7E„1 Protocol element comparison of RTS

RTS element NBS A/311 A/3211 PROBLEM Y/N

PConnect M M M N

DataTransferSyntax M 0 M 0 M 0 N

PUserData M M M N

checkpoints ize H H H N

windows ize H H H N

dialogueMode H H H N

connectdata M M M N

applicationProtocol G 1 H 8883

H 1 R 8883 N

Connect ionData

Open G G ? ? A/3211 undefined

Recover G H ? Y Conformance (E)

Open

RTSUserData G G G N

Recover

SessionConnectionID G G G N

RTSUserData

MTAName G G G N

Password G G G N

null G G G N

SessionConnectionID

CallingUserReference M M M N

CommonReference M M M N

AdditionalReflnfo H H H N

PAccept G G G N

DataTransferSyntax M 0 M 0 M 0 N

(Continued on next page.)

7-80
Table 7E.1 Protocol element comparison of RTS, continued

RTS element NBS A/311 A/3211 PROBLEM (Y/N)

PUserData M M M N

Checkpoints ize H H H N

WindowSize H H H N

ConnectionData M M M N

PRefuse G G G N

RefuseReason M M M N

SSUserData G G G N

(in S -TOKEN- PLEASE)

Abort Information G G G N

(in S-U-ABORT) - AbortReason H H H N

ref lectedParameter’ X X X N

7-81
Table 7E.2 Protocol element comparison of PI

PI Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

ORname

StandardAttributeList M M M M N See Note 4

DomainDefAttributeList X X X G Y See Note 5

StandardAttributeList

CountryName R R R M N

ISO R R N

X.121 H H Y Conformance (E)

Other X X Y Prot Vio

AdministrationDomainName R R G M N

... if PrintableString R G N

..." if numericString H H Y Conformance (E)

X.121 Address X- X/R X Y Conf (US)See Note 1 Terminal ID X X/G X Y Conf (US)See Note 1 Pr i vateDoma inName G G G G N

OrganizationName G G G G N

UniqueUAidentif ier X X/G X Y Conf (US)See Note 1 PersonalName G G G G N

OrganizationalUnit G G G G N

DomainDef inedAttribute X X X G N

Type M M M M N

Value M M M M N

PersonalName

Surname M M M M N

GivenName G G G G N

Initials G G G G N

GenerationQualif ier G X X X Y Conformance (E)

GlobalDomainldentif ier

CountryName M M M M N

AdministrationDomainName M M G M Y Proto Vio

PrivateDoma inidentifier R/H H R M/X N

MPDU

UserMPDU G G G G Y TTC required

MPDU size is

32K

DeliveryReportMPDU G G G G N

ProbeMPDU H H H H N

(Continued on next page.

7-82
I

Table 7E.2 Protocol element comparison of PI, continued

PI Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

UserMPDU

UMPDUenve lope M M M M N

UMPDUcontent M M M M N

UMPDUenve lope

MPDUidentifier M M M M N

originatorORname M M M M N

originalEncodedTypes G H H G Y Conformance (E)

ContentType M M M M N

UAcontentID H H H - H N

Priority -G G G G N

PerMessageFlag G G G G N

DeferredDe livery X X X • X N

PerDomainBilatlnfo X X X X N

Recipientlnfo M M M M Y TTC MPDU 32K

Tracelnformation M M M M N

MOTIS-> LatestDelivery X N

MOTIS-> InternalTracelnfo M/P P N

UMPDUcontent M M M N

MPDUidentifier

GlobalDomainldent M M M M N

IA5string M M M M N

PerMessageFlag

DiscloseRecipients H G @ MTL H H Y Conformance (US)

H at UA ? Y Conformance (US)

ConversionProhibited G G G G N

AlternatRecipAl lowed H G @ MTL H X Y Conformance (US)

H at UA ? Y Conformance (US)

ContentReturnRequest X X X

MOTIS-> redirectionProhibited X N

PerDomainBilaterallnfo

CountryName M M M M N

AdminDomainName M M G M Y Prot Vio

MOTIS-> PrivateDomainName G N

Bilaterallnfo M M M M N

(Continued on next page

7-83
Table 7E„2 Protocol element comparison of PI, continued

PI Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

DeliveryReportContent

original MPDUident M M M M N

intermediate Trace X/G X X X Y Conformance (E)

UAcontentID G G G G N

ReportedRecipientlnfo M M M M Y TTC 256 max

returned H H X X Y Conformance (E)

billing information X X X X N

ReportedRecipientlnfo

recipient ORname M M M M N

extensions Identifier M M M M N

PerRecipientFlag M M M M N

LastTracelnformation M M

' M M N

intendedRecipient H- H H H N

Supplementarylnfo X/H X X X Y Conformance (E)

MOTIS-> ReassignmentInfo X N

MOTIS-> Reass ignmentlnfo

MOTIS-> intendedRecipient M N

MOTIS-> reasonForReassignment H N

LastTracelnformation

arrival M M M M N

convertedEncInfoTypes G G H G Y Conformance (E)

Report M M M M N

Report

Deliveredlnfo G G G

“U

N See Note 6

NonDeliveredlnf

G G G _r N

Deliveredlnfo

delivery M M M M N

TypeofUA R/H H R M/G N

NonDeliveredlnfo

ReasonCode M M M M N

DiagnosticCode H H H H N

MOTIS-> UAprof ileldentif ier X N

MOTTS -> UAprof ileldentif ier

MOTIS-> ContentType M N

MGTIS-> EncodedlnfoTypes M N

(Continued on next page

7-84
Table 7E.2 Protocol element comparison of PI, continued

PI Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

ProbeEnvelope

probe M M M M N

originator M M M M N

ContentType M M M M N

UAcontentID H H H H N

originalEncInfoTypes G H H G Y Conformance (E)

Trace Informat ion M M M M N

PerMessageFlag G G G G N

ContentLength H H H H N

PerDomainBilatlnfo X X X X N

Recipientlnfo M M M M Y TTC 256 max

MOTIS-> InternalTracelnfo M/P P N

Recipientlnfo

RecipientORname M M M M N

Extensionldentifier M M M M N

PerRecipientFlag M M M M N

ExplicitConversion X X X X N

MOTIS -> OriginatorReqAlternatRecip X N

MOTIS-> Reass ignmentlnfo X N

PerRecipientFlag

ResponsibilityFlag M M M M N

ReportRequest M M M M N

UserReportRequest M M M M N

Trace Informat ion

GlobalDomainldent M M M M N

DomainSuppliedlnfo M M M M N

(Continued on next page

7-85
Table 7E.2 Protocol element comparison of PI, continued

PI Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

DomainSuppliedlnfo

arrival M M M M N

deferred X X X X N

action M M M M N

(0=relayed) G G G N Note:

Re-routing not

required.

(l=rerouted) H H H N

MOTIS-> (2=recipientReassigned) H N

converted H G H H Y Conformance (US)

previous H G G X Y Conformance (US

)

(Note: G is

. „ inconsistent with

action (relayed)

being "H" .

)

ORname

EncodedlnformationTypes

BitString M M M M N See Note 3

GSNonBasicParameters X X X X N

TeletexNonBasicParams X R X X Y Conformance (US)

PresentationAbilities X X X X N

De 1 iveryReportMPDU G G M G N

DeliveryReportEnvelop M M M M N

DeliveryReportContent M M M M N

DeliveryReportEnvelope

report M M M M N

originator ORname M M M M N

Trace Informat ion M M M M N

InternalTracelnfo M/P P N

(Continued on next page

7-86
Table 7E.3 Protocol element comparison of P2

P2 Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

UAPDU

IM UAPDU G G G G N

SRJJAPDU X X X X N

IM UAPDU

Heading M M M M N

Body M M M M N

Heading

IPmessagelD M M M M N

Originator ORname R R R M/G N

Author IzingUsers H H H H Y TTC 16 max

Pr imaryRec ip ientG. G G G Y TTC 256 max

CopyRecipients G G G G Y TTC 256 max

BlindCopyRecipients H H H H Y TTC 256 max

InReplyTo G G G G N

Obsoletes H H H H Y TTC 8 max

CrossReferences H H H H Y TTC 8 max

Subject G G G G N

ExpiryDate H H H H N

ReplyBy H H H H N

ReplyToUsers H H H H Y TTC 32 max

Importance H H H H N

Sensitivity H H H H N

Autoforwarded H H H H N

MOTIS-> CirculationList X N

MOTIS-> ObsoletingTime X N

IPmessagelD

ORpame H H H H N

PrintableString M M M M N

ORdescriptor

ORname H H H

“U

N See Note 6

FreeFormName H H H _r N

TelephoneNumber H H H G N

Recipient

ORdescriptor M M M M N

ReportRequest X X X X N

ReplyRequest H H H H N

(Continued on next page.)

7-87
Table 7E.3 Protocol element comparison of P2, continued

P2 Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

M0TIS-> CirculationList

MOTIS-> CirculationMember X N

M0TIS-> checkmark M N

MOTIS-> membername M N

MOTIS-> OBsoletingTime

MOTIS-> Time H N

MOTIS-> IP_MessageID H N

Body

BodyPart G M M G Y Conformance (US)

SR UAPDU . NonReceipt H. H H

“U

N

• Receipt H H H _r N

Reported M M M M N

ActualRec ip ient R R R G N

IntendedRec ip ient H H H H N

Converted X X X G N

MOTIS-> CirculationStatus X N

NonReceiptlnformation

Reason M M M M N

NonReceiptQualif ier H H H H N

=expired (value) 0 0 0 0 N

=obsoleted (value) 1 1 1 1 N

=subscriptionTerminated 2 2 2 2 N

MOTIS-> =t imeobsoleted (value) X N

Comments H H H X N

returned H X X X Y Conformance (E)

ReceiptInformat ion

Receipt M M M M N

TypeOfReceipt H H H G N

Supplementarylnfo X X X X N

(Continued on next page.)

7-88
Table 7E.3 Protocol element comparison of P2, continued

P2 Protocol NBS A/311 A/3211 TTC PROBLEM (Y/N)

BODYPART SUPPORT

o IA5 Text G G G N See Note 7 o TLX X X X N

o Voice X X X N

o G3FAX X X X N

o TIFO X X X N

o TTX X X/H X Y Conf (US )See Note 2

o VideoTex X X X N

o NationallyDef ined X X X N

o Encrypted X X X f N

o. ForwardedIPmessage H H H N

o SFD X. X X N

o TIFI X X X N

MOTIS -> o ODA X N

MOTIS -> o IS06937 Text H N

Note 1: It should be noted that the A/113 profile states: For routing

all ADMDs should support all Form 1 Variants of 0/R Name. All

PRMDs should support at least Form 1, Variant 1 form of OR Name.

Note 2: It should also be noted that the A/311 profile requires that all

ADMDs should support the reception of Teletex body parts for

delivery to their own UAEs.

Note 3: An A/3211 implementation may generate MOTIS encoded information

types. See 7.6.11.

Note 4: Only Form 1 Variant 1 of O/Rname shown for TTC, but TTC defines

other forms and variants. Form 1 Variant 1 recommended for PRMDs

and ADMDs, Form 1 Variant 2 also recommended for ADMDs.

Note 5: DDA's can be used to specify recipients in any domains other than

TTC. Assignment of DDAs for UAs within TTC domains is not

recommended.

Note 6: One of [Deliveredlnfo/NonDeliveredlnfo] must be present. TTC

encodes this as shown. Other profiles represent this by

classifying both protocol elements as gereratable. A similar

situation exists with the P2 ORdescriptor

Note 7: TTC is expected to support IA5 for international MHS

communications

7-89
7.16 APPENDIX F: INTERWORKING WARNINGS

ADMD name is to be encoded as a single space when configurations with

no ADMD's are present. It should be noted that this may change in

January 1988 so that the ADMD name is encoded as a zero length element

in such cases.

The NBS agreements allow implementation to generate MPDU's with no

body parts. Such MPDU's will be rejected by European- conformant

systems. (Note this situation may change in January 1988)

In order to optimize the number of recipients you can read and reply

to, it is advisable to be able to generate all standard OR name

attributes

7-90
8. DIRECTORY SERVICES PROTOCOLS

8.1 INTRODUCTION

This is an Implementation Agreement developed by the Implementor's

Workshop sponsored by the U.S. National Bureau of Standards to promote

the useful exchange of data between devices manufactured by different

vendors. This agreement is based on and employs protocols developed

in accord with the OSI Reference Model. While this agreement

introduces no new protocols, it eliminates ambiguities in

interpretations

This is an Implementation Agreement for Directories based on the 1988

Recommendations/International Standard from the CCITT and ISO joint

working groups on Directories (hereafter referenced as Directory

Documents). Versions of this document will stay consistent with the

latest drafts of those Directory Documents. Figure 8.1 displays the

structure of this Implementation Agreement.

Directory Access Protocol Directory System Protocol

(DAP) (DSP)

Remote Operations Services and Protocols

(CCITT X. 219 and X. 229/ISO 9072/1 and 9072/2)

Association Control Services and Protocols

(CCITT X. 217 and X. 227/ISO 8649 and 8650)

Figure 8.1 Structure of this Implementation Agreement

The Directory User Agents (DUAs) and Directory Service Agents (DSAs)

provide access to the Directory on behalf of humans and applications

such as Message Handling and File Transfer, Access, and Management.

See the Scope and Field of Application section for more information on

the model used in Directories.

This document covers both the Directory Access Protocol (DAP) and the

Directory System Protocol(DSP) defined in the Directory documents. A

good working knowledge of the Directory documents is assumed by this

chapter. All terminology and abbreviations used but not defined in

this text may be found in those documents

8,2 SCOPE AND FIELD OF APPLICATION

Stand alone and distributed directories can both be accommodated in

this Agreement by the appropriate choice of protocols and pragmatic

constraints from those specified. Figure 8.2 illustrates a stand

alone directory and Figure 8.3 illustrates a distributed directory.

8-1
This agreement does not cover interaction between co-located entities,

such as a co-resident DUA and DSA. It also does not specify the

interface between a user (person or application) and a DUA.

Bilateral agreements between a QUA and DSA or DSA and DSA may be

implemented in addition to the requirements stated in this document.

Conformance to this agrement requires the ability to interact without

the use of bilateral agreements other than those required in the

Directory documents

The external appearance of the Directory Information Base (DIB) will

be in conformance with the Directory documents . The manner in which a local portion of the DIB is organized and accessed by its DSA is not

in the scope of this agreement.

Directory Environment

The Directory

DSA

USER S X DUA

USER UU/i HIT A

Figure 8.2 Stand-alone Directory Model

8-2
Directory Environment

Figure 8.3 Distributed Directory Model

8.3 STATUS AND REFERENCES

This Implementation Agreement is conformant with the following ISO and

CCITT documents; the Directory documents are in a second DP process.

The Directory- -Overview of Concepts, Models, and Services (CCITT

Recommendation X.500, ISO 9594/1)

The Directory- -Information Framework (CCITT Recommendation X.501,

ISO 9594/2)

The Directory- -Access and System Services Definition (CCITT

Recommendation X.511, ISO 9594/3)

The Directory- -Procedures For Distributed Operation (CCITT

Recommendation X.518, ISO 9594/4)

The Directory- -Access and System Protocols Specification (CCITT

Recommendation X.519, ISO 9594/5)

The Directory- -Selected Attribute Types (CCITT Recommendation

X.520, ISO 9594/6)

8-3
The Directory- -Selected Object Classes (CCITT Recommendation

X.521, ISO 9594/7)

The Directory- -Authentication Framework (CCITT Recommendation

X. 509 , ISO 9594/8)

Remote Operations-Part 1: Model, Notation and Service Definition

(CCITT Recommendation X.219, ISO 9072/1)

Remote Operations-Part 2: Protocol Specification (CCITT

Recommendation X.229, ISO 9072/2)

Association Control-Service Definition (CCITT Recommendation

X219 , ISO 8649/2)

Association Control-Protocol Definition (CCITT Recommendation

X. 229 , ISO 8650/2)

8 . 4 Use of Directories

Given the rapid multiplication and expansion of OSI applications,

Telecommunication Systems and Services, there is growing need for

users of, as well as the applications themselves, to communicate with

each other. In order to facilitate their communications, a Directory

protocol, as referenced in these agreements, has been tailored to meet

their respective needs.

In one instance, Directories will be used as a service to provide

humans, in an on-line fashion, rapid and easy retrieval information

useful for determining what telecommunications services are available,

and/or how to access, and address their correspondents. Further,

Service Providers offering such a Directory publicly may also use this

service internally with other various telecommunications services (eg.

MHS ) for the proper addressing of calls or messages. Likewise, this

does not preclude the usage of these agreements to similarly generate

a privately operated Directory that supports both human and

application information exchanges.

In another instance, Directories, will be used as a service by

computer applications without direct human involvement. One important

service is to provide Presentation Address (PSAP) translation for

named objects, on behalf of network and facility management. The

directory may be used by applications to search for objects (i.e.,

Application Entities), again without direct human involvement, by the

use of the ''search'' or ''list'' operations. Although human can

''search'' in a complex manner, ''search'' may also be used in a

simple manner by application software, perhaps using a predefined

logical pattern, to search for objects with the particular capability

required by the application.

8-4
To support the many possible usages, the Directory must be a general

purpose system. It must be capable of storing data of many different

forms as attributes within entries, and must also be capable of

supporting simple or complex hierarchical structures, with variations

.in structure possible occurring between one part of the Directory and

another

Compliant DSA implementations should safeguard this generality, where

possible, by placing the minimum of restrictions in '’hard-wired''

form. The Directory permits the imposition of rules by means of the

Directory Schema (Section 10.6 below); but the Directory Schema

itself should be capable of alteration by Directory management.

8 . 5 Directory ASEs. Application Contexts, and Ports

The functionality of the Directory AEs (DUAs and DSAs) is defined by a set of ASEs, each Directory ASE specifying a set of Directory

operations.

The interaction between these AEs is described in terms of their use

of ASEs. This specific combination of a set of ASEs and the rules for

their usage defines an application context.

Thus, each Directory application context defines the operations needed

by two communicating Directory entities

Access to the services provided by an application context is through

one or more directory ports . The point of access is called an Access

Point (see Figure 8.4). Each access point corresponds to a particular

combination of port types.

The following ASEs are described in the Directory Document:

o Directory Read ASE

o Directory Chained Read ASE

o Directory Search ASE

o Directory Chained Search ASE

o Directory Modify ASE

o Directory Chained Modify ASE

ROSE and ACSE also form part of the Directory Application Contexts.

The following Application Contexts are described in the Directory

Document

o Directory Read Application Context

o Directory Read and Search Application Context

o Directory Read and Modify Application Context

o Directory Read, Search, and Modify Application Context

o Directory Chained Application Context

8-5
The following Ports are described in the Directory Document:

o Read Port

o Modify Port

o Search Port

o Chained Read Port

o Chained Search Port

o Chained Modify Port

The ports cited above are to be specified for a particulat Access

Point to the Directory as illustrated by Figure 8.4.

Figure 8.4 Access to the Directory

8 . 6 Schemas

There are four (4) major topics that relate to schemas:

8.6.1 Maintenance of structure and naming rules

DSAs shall be able to support the storage and use of structure

and naming rules defined in Part 7 of the Directory documents.

8.6.2 Maintenance of object classes and subclasses

DSAs shall be able to support not only the storage and use of

object classes defined in Part 7, but also the modification and

extension mechanisms provided by sub-classes (or other means

permitted by Part 2) as provided by local implementation.

8-6
8.6.3 Maintenance of Attribute Tvr>es

DSAs shall be able to support the storage and use of attribute

type information, as defined in Part 6, including their use in

naming and access to entries; they shall also support the

definition of new attribute types, making use of pre-existing

attribute syntaxes.

8.6.4 Maintenance of Attribute Syntaxes

Suggested methods for the maintenance of selected Attribute

Syntaxes is defined in Appendix B.

8 . 7 Classification of Support for Attribute Types

This section classifies directory support for selected attribute type

specified in the Directory documents.

Classification of support for selected attribute types is either

mandatory or optional.

8.7.1 Mandatory Support

The Directory must be able to support these Attribute Types:

Aliased Object Name

Business Category

Common Name

Country Name

Facsimile Telephone Number

Locality Name

ISDN Address

Member

Object Class

Organization Name

Organization Unit Name

Owner

Postal Address

Postal Code

Presentation Address

Role Occupant

See Also

Serial Number

Teletex Number

Telephone Number

Telex Number

Title

User Password

X.121 Address

Note: Support of these Attribute Types implies full support of

the relevant Attribute Syntaxes.

8.7.2 Optional Support

Directory support of these attribute types is considered

optional

Search Guide

Description

8-7

Teletex Non-Basic Parameter

Teletex Terminal ID
G 3 Non-Basic Parameter T.73 Presentation Capabilities

Knowledge Information

Note: DSAs should consider initial support of the Attribute

Syntax relevant to any Attribute Type for which future support is

planned, in addition to those required for mandatory Attribute

Types

8 . 8 Introduction to Pragmatic Constraints

The following sections of this document define the pragmatic

constraints to which a conformant implementation must adhere. The

pragmatic constraints are divided into two areas. The first includes

those aspects of pragmatic constraints which apply to the scope of

service. The second includes those aspects of pragmatic constraints

which are specific to particular attribute types.

8 . 9 Pragmatic Constraints the Directory Service

8.9.1 Character Sets

There is a requirement to support all character sets and other

name forms defined in the Directory Documents Part 6 . Those

character sets include:

o T. 61

o PrintableString

o NumericS tring

8.9.2 APDU Size Considerations

In the process of chaining requests it is possible that a

chaining DSA may receive invoke or return APDUs that exceed its

capacity:

Figure 8 . 5 APDU Exchange

8-8
It is a minimum requirement that invoke and return result APDUs

must be accepted unless they exceed 32767 octets in size; in

this case they may be discarded as illustrated in the right side

of figure 8.5, and an ’' unwillingToPerform' ' error reporting

service shall be used.

8.9.3 Service Control (SO Considerations

This agreement recognizes that DUAs may automatically supply

defaults for any SC parameter. The choice of default values

selected (if any) is seen to be a matter of local policy and

consumer needs.

It should be noted that certain combinations of SCs are counter

productive, e.g., if the following SCs are chosen for a '’Search'' operation (Priority=LOW; TimeLimit=2 Seconds;

Chaining=Preferred) , the operation will probably result in

failure when the operation is chained.

8.9.4

Size Limit Service Control

There are actually two (2) SC parameters (SizeLimit, ListCount)

that may be specified to control the number of objects returned

to a DUA as a production of' 'List'' or ''Search'' operation. If

the operation returns more objects to the requestor DSA than

specified in the SC SizeLimit parameter, the DSA discards the

results and returns to the requestor DUA in the Service Error

result parameter the appropriate Service Problem (i.e.,

sizeLimitExceeded) and if SC listCount was also specified on the

original request the Service Error result parameter also

includes, in the lists ize argument, a count of the total number

of objects found to match the requestors criteria.

8.9.5

Priority Service Control

Priority is specified as a service control argument in the

Directory documents. The following statements represent a

clarification of the semantics that may be used by a DSA in

interpreting and operating on this parameter.

The logical model in Figure 10.6 may be considered as an example

by DSAs that implement this Service Control.

o The DSA maintains three logical queues corresponding to

the three priority levels.

o The DSA Scheduler is separate and distinct from any

scheduling function provided by the underlying

operating system or control program services.

8-9
o The DSA Scheduler presents jobs to the Underlying

Operating Services for execution and always present

jobs of a higher priority before those of a lower

priority.

o The DSA Scheduler will not preempt a request once it

has been passed to the underlying operating system

service

Figure 8.6 Logical DSA Application Environment

8 . 10 Constraints on Operations

There are no overall constraints upon service arguments or results

except those implied in section 10.9.2 of this document.

8,10.1 Filters

It is required that DSAs, at a minimum, support 8 nested

'' Filter '' parameters, and a total limit of 32 Filter Items. If

these limits are exceeded, the recipient of that SearchArgument

may return the ServiceProblem '' unwillingToPerform' '

8.10.2 Errors

There are no constraints upon any Error service except that if

this implies the handling of operation APDUs larger than 32767

octets (as described in section 10.9) a service error

'

’ unwillingToPerform' ' can be returned in accordance with section

8.9.2.

8-10
8.11 Pragmatic Constraints on Attribute Types

This section defines the pragmatic constraints specific to particular

attribute types.

8.11.1

Attribute Values

This section describes the pragmatic constraints for attribute

values. Each constraint is given in terms of a Length

Constraint. The Length Constraint for a given attribute value is

the number of units which a sending entity must not exceed and

which a receiving entity must accept and process. A sending

entity need not be capable of sending attribute values as large

as8.11.2 the Length Constraints.

Use of Pragmatic Constraints for Strings

The Length Constraint for strings is expressed as the number of

allowable characters and the number of allowable octets. When

using the Printable String ASN.l data type, the number of octets

equals the number of characters. When using the T.61 ASN.l data

type, the number of octets is twice the number of characters.

This is because some T.61 characters occupy two octets per

character

8.11.3

Attribute Types

Tables 8.1 and 8.2 specify the pragmatic constraints for selected

attribute type specified in the Directory documents.

8-11
I

Table 8.1 Pragmatic Constraints for Selected Attributes. Part 1

Attribute Type Content Number

of

Printable

Characters

Number

of

Allowable

Octets

Status Notes

Object Class Obj ect

Identifier

256

Common Name T.61 or

Printable

String

64 128 X. 500

Serial Number Printable

String

64 64 X. 500

Country Name T.61,

Printable

,

or Numeric

String

64 128 ISO 3166

and CCITT

X. 121 Allow

for long- form

X. 500

Locality T.61 or

Printable

String

128 256 X. 500

Postal

Address

T.61 or

Printable

String

30 x 6 60 x 6 Note 5

X. 500 & UPU

Postal Code T.61 or

Printable

String

40 40 UPU

X. 500

Organization

Name

T.61 or

Printable

String

64 128 X. 500

Organizational

Unit Name

T.61 or

Printable

String

64 128 X. 500

Title T.61 or

Printable

String

64 128 X. 500

8-12
Table 8.1 Pragmatic Constraints for Selected Attributes. Part 1 (continued)

Attribute Type Content Number

of

Printable

Characters

Number

of

Allowable

Octets

Status Notes

Title T.61 or

Printable

String

64 128 X. 500

Description T.61 or

Printable

String

1024 2048 X.500 About

1 Screen full

Search Guide ffs

Business Category T.61 or

Printable

String

64 128

Facsimile Telephone NumberPrintable

String

32 32 CCITT E.163

X.500

ISDN Address Octet

String

n/a 16+40 Note 2. CCITT

E. 164 X.500

Presentation

Address

Presentation

Address

n/a 224 Note 3, ISO 7498

X.500, & X. 200

Telephone

Number

Printable

String

32 32 CCITT E.163

X.500

Teletex Terminal

Identifier

Printable

String

24 24 CCITT F.200

X.500

Telex Number Numeric 14 14

CCITT X.500

X. 121

X.121 Address Numeric 15 15 CCITT X.121

X.500

G 3 Non-basic

Parameters

Octet

String

n/a 4 CCITT T30

(32 bits) X.500

8-13
Table 8.1 Pragmatic Constraints For Selected Attributes, (continued)

Attribute Type Content Number

of

Printable

Characters

Number

of

Allowable

Octets

Status Notes

Teletex Nonbasie ParametersOctet

String

n/a 64 CCITT X. 500

T . 62 (59+Fudge

Factor)

T.73 Presentation CapabilitiesOctet

String

Note 1 CCITT T.73

Member Distinguished _ Name —

Note 4

Owner Distinguished

Name

Note 4

Role

Occupant

Distinguished

Name

Note 4

See Also Distinguished

Name

Note 4

User

Password

Octet

String

n/a 128 X.500 Allow

long passwords.

Machine

Generated

Aliased Object

Name

Distinguished

Name

Note 4

Knowledge

Information

T.61 or

Printable

String

1024 2048 About 1 screen full,

ffs

Structure ffs

Street Address T.61 or

Reference

UPU. Component

of Postal

Address

8-14
Notes

1. The pragmatic constraints of these parameters are defined in

other standards. We will accommodate these values in our

pragmatic constraints.

2. There appears to be an error in the Directory documents part 6,

on interpretation of this attribute. (The Directory document

defines this as telephone number)

3. Presentation address is composed of ''X'' NSAP addresses, and

three selectors, (20X + 32 + 16 + 16 ) , e.g. if X = 1 , this would

be 84. These numbers are based on the most recent implementor's

agreements. With 8 NSAP addresses this value is 224.

4. Pragmatic constraints are only applied to the individual

components of DistinguishedName as defined in the Directory

Documents Part 2.

5. Implementors should be aware that constraints on Postal Address

may not be sufficient for some markets.

8.12 Conformance

The following sections will describe various aspects of Directory

conformance. It should be noted that conformance to the various ASEs

and conformance to the Authentication Framework are viewed as separate

issues and are presented in that context.

8.12.1 DUA Conformance

The primary requirement for each DUA is that is must comply with

the DAP for each function that it supports. This requirement is

adequately formalized by the Directory documents, part 5, section

11.1. It should be noted that DUA conformance can only be

demonstrated by exercising the interface that it provides to its

user. This interface shall be specified and documented by the

implementor

It is recognized that DUAs will be widely differing in nature:

o Some are intended to support human users, some application

users

o Particular DUAs may not support particular operations

because the application that they support has no

requirement; others will be general purpose, and will

support all operations.

8-15
o Some DUAs will have a fixed view of the Directory content

and structure, reflecting the usage of the Directory by a particular application; others will have a more flexible

view which can be adapted to new usages

o Some DUAs will provide automatic referral services with

automatic establishment and release of associations; others

will place the burden on the user.

o Some DUAs will provide a variety of authentication means;

others will support simple authentication only

o Some DUAs will handle operations synchronously; others will

have the capability of maintaining several identifiable

dialogues with the Directory at one time.

No general implementation agreements are spelled out in respect

of these possibilities.

8,12.2 PSA Conformance

Standalone

A standalone DSA is defined as one that contains its entire

relevant DIT; it follows that it will not make use of the DSP or

generate referral responses. Since this model only contains a

single DSA it is not subject to DSA interworking issues and will

always provide a consistent level of service and results. A

standalone DSA must be fully ''protocol'' conformant to the DAP.

Cooperating

In a distributed directory, responsibility for various portions

of the DIT may be ''distributed'' among multiple DSAs . On a per

operation basis we define a DSA to be ' 'holding' ' when it is

responsible for the fragment of the DIB in which a given entry

will appear if it exists; we define a DSA to be ''propagating''

when it is unable to complete the name resolution process. All

DSAs must be capable of acting as a

' 'holder' ' and

a' 'propagator. '

A cooperating DSA must be fully ' 'protocol' ' conformant to both

the DAP and DSP as defined in the Directory documents part 5

Sections 11.2.2 and 11.2.3.

Protocol Conformance

It is required that a

' 'propagating' ' DSA will either refer,

chain or multicast requests for operations regardless of how it

would act upon the operation were it the ' 'holder. '

A DSA must

accept all associations because no predetermination can be made

8-16
as to its role as a

' 'propagator' ' or ' 'holder' ' for any

subsequent operation requests.

8.12.3 Rationale for ''Conformance''

This level of support is required in order to obtain consistent

behavior from the operations, independent of the particular DSAs

involved.

To illustrate the interworking problem caused by a non

''protocol'' conformant DSA consider the following example as

illustrated in figure 8.7:

2

Figure 8.7 DSA Interworking

In the above figure DSA 4 is a

' 'holding' ' DSA for a certain

entry. An initiator (DUA or DSA) directs an operation on that

entry to DSA 2; if DSA 2 is ''protocol'' conformant it will

either chain or refer the operation to another DSA which will in

turn either handle the operation or proagate it again in the

direction of the holding DSA.

The scenario would be the same for DSA 3 assuming it is also

''protocol'' conformant. If, however, DSA 3, is not protocol

conformant and refuses an association for a given application

context an initiator will experience inconsistent results

depending on which DSAs an operation involves. This is not an

acceptable interworking situation.

In a situation where a DSA determines that it is ' 'holding'

and

it does not support an operation it may choose to return an

unwillingToPerform error.

Note: The usa of ''unwillingToPerform'' is not the appropriate

error. An ' 'unsupported' ' error is needed.

at may choose to respond to an operation that it does not support

in a number of ways. It may generate an AccessViolation or an

8-17
Unsupported error. Generation of an AccessViolation is

considered acceptable since in fact no one is allowed to perform

that operation on the entry. It is not relevant that access can

not be granted. Which method of response to be recommended in

this situation is For Further Study.

Functional Conformance

DSAs adhering to the rules for '' protocol '' conformance may in

theory choose to implement any subset of the available ASEs. An

implementation, whether standalone or cooperating, is said to be

''functionally'' conformant to an ASE if it is able to process

the operations as the ' 'holding' ' DSA.

Conformance classes of the following ASEs are not perceived to be

satisfactory because they do not meet the minimum OSI

requirements of the application layer:

o Read only Directory System

o Search only Directory System

o Modify only Directory System

o Search and Modify Directory System

The complexity involved in implementing an acceptably functional

DSA is not sufficient reason to reduce the functionality of the

Directory System. If it is undesirable to allow modification of

the DIB the (local) AccessControl mechanism are sufficient enough

means to facilitate this restriction.

8.12.4 Directory Systems Conformance Classes

As a result there are two (2) conformance classes:

o Read / Modify

o Read / Modify / Search

The Read/Modify Directory System meets the minimal requirements

of MAP/TOP providing the ability to map from, for example,

AE-Title to Presentation address.

The Read/Search/Modify Directory System is a fully functional

implementation.

Note: There are interworking issues between the two conformance

classes. Search operations involving DSAs not supporting search

may yield incomplete results.

8-18
8.12.5 Authentication Conformance

A Directory System may choose to implement various levels of

authentication (Directory documents part 8) . We define the

following four (4) levels of authentication in the DS

o No authentication at all; ( None )

o Identification of the remote peer entity only, without

verification; ( Weak)

o Simple authentication: identification with verification

intended to make masquerading difficult; and

o Strong authentication: identification with verification

using cryptographic techniques intended to make

masquerading, in practical terms, nearly impossible.

Note: The above definitions appear in editing notes for ISO 8649

(ACSE authentication description)

The Authentication Framework document describes the specific goal

of each authentication level; we have listed several practical

uses of the various levels:

NONE: No authentication may be required for associations with

a DSA containing public information: DSAs operating on

a private network in a controlled environment may

implicitly trust all connections and have no

requirement for authentication.

WEAK authentication may be desired to maintain access

statistics or in a private network where the initiator

is implicitly trusted and there is no need to incur the

additional overhead of more sophisticated

authentication methods.

SIMPLE authentication may be necessary in situations where

strong authentication is not practical, (i.e.:

international connections, no knowledge of algorithms

in use , etc)

STRONG authentication will be required for secure

environments

8-19
8 . 12.6 Authentication Conformance Classes

We define the following two (2) conformance classes for the

support of authentication:

o None, Weak, and Simple

o None, Weak, Simple, and Strong

It should be noted, as described in the Directory documents part

8 Section 6.2, that in the absence of bilateral agreements

potential interworking problems exist between DSAs using strong

authentication

Note: Serious consideration should be given to the potential

interworking problems that will arise when attempting a chained

or multicast operation across a distributed DIB requiring

multiple levels of authentication.

The topic of strong authentication is subject to change pending

future CCITT and ISO work in this area.

8.13 Distributed Operations

The following requirements apply to DSAs supporting distributed

operations

1. DSAs must support the generation of referrals.

2. DSAs may additionally support chaining. DSAs that only support

chaining (i.e. no referrals) are not allowed.

3. DSAs supporting authentication (e.g. simple authentication by

name and password) must be able to invoke DSP operations to carry

out authentication by reference to other DSAs. Thus all such

DSAs must support the DSP protocol.

8.13.1 Referrals and Chaining

It is recommended that a DSA which has chained a request act upon

any referrals it receives rather that returning them to the

requestor if the '' PreferChaining' ' service control is present.

8 . 14 Underlying Services Assumed

This section describes the Directory requirements from ROSE, ACSE,

Presentation and Session.

8-20
8.14.1 ROSE

All Directory operations are mapped on the ROSE services. In

order to support the Directory protocols, the ROSE provider must

support, as a minimum, the following services:

Association Class 1 . for all associations in the DAP and DSP

protocols. In the DAP, the DUA is always the consumer of

services, and it alone can initiate (Bind) and terminate (UnBind)

associations. In the DSP, the initiating DSA is always the

consumer, and the responding DSA the supplier. Only the

initiating DSA may release (UnBind) an association.

Operation Classes 1 and 2 - All Directory operations are

confirmed always returning a result or an error. The Directory

supplier agents (DSAs) must be capable of invoking operations and

receiving results in an asynchronous fashion and therefore

require the use of operation class 2. The Directory consumer

agents (DUAs) on the other hand, must support Operation Class 1 (synchronous operations) and may alternatively support operation

class 2.

The use of operation class 2 implies that Invoke-IDs must

increase monotonically for all operations within a Directory

application association. However, the Invoke-IDs need only be

unique for the duration of a given application association (i.e.

uniqueness is not required across consecutive application

associations)

8.14,2 ACSE

The Bind and UnBind operations map on a subset of ACSE services,

as defined in the Directory documents.

Additionally, the Directory makes use of the A-ABORT service to

force the abnormal termination of an application association.

For example, if a supplier DSA wants to release an inactive

association (because of depletion of local resources, for

instance) it cannot UnBind it since only the initiator may

release the association. The only way to terminate the

association is thus aborting it with an A-ABORT primitive.

It is expected that DSAs will support multiple application

associations

8-21
8.14.3 Presentation

The presentation kernal functional unit and multiple presentation

contexts are required.

8.14.4 Session

The directory requires the use of the Kernel and Duplex

functional units

A DSA implementation is required to support version 2 of the

session protocol, and must also be capable of supporting version

1 .

A DUA implementation my use version 1, version 2, or both.

Note: DUAs supporting user authentication may require session

version 2, because of the potentially large size of the Bind

credentials

8.15

Access Control

The contents of this section are for further study.

The issue of Access Control is currently a local implementation

matter. The following items should be considered as a strawman for

future work in this area:

o Granularity of Control

o Access Rights Categories

o Use of Authentication

o Distribution of Knowledge on Access Rights

o Local and Remote Access Mechanism

8.16

Authentication

The contents of this section are for further study with respect to

weak, simple and strong authentication.

8,17

Data Security

The contents of this section are for further study with respect to

encryption and digitally signed results.

8-22
8.18 Test Requirements

Temporary Note: This material is in the form of a strawman to

facilitate future discussion on this topic. It is not expected that

this will be completed for the first version of the implementors

agreements

8.18.1 Major elements of Architecture

One important aspect of testing is to confirm the correct

behavior of DSAs and DUAs in respect of major elements of the

directory architecture.

Such major elements include:

o Distinguished names (e.g., name resolution, equivalence of

various forms)

o Entries and Attributes (e.g., accessibility by operations,

compliance with rules)

o Naming contexts and knowledge (e.g., handling of distributed

operations)

o Schemas

Structure rules (e.g., storage and maintenance of

structure and of naming)

Object classes and sub-classes (e.g., storage and

extension of rules for object attributes)

i Attribute types (e.g., storage and maintenance of

syntax classes and rules for multi or single valued

attributes)

Attribute syntax (e.g. maintenance and support for

attribute value testing and matching, to specification

for a defined set of attribute types)

o Operations **

' 'read' '/' 'compare'

(correct function / result / error

responses)

''abandon'' (correct function)

'' list' '/'' search'(correct function / result / error

responses)

'

' add- entry ' '/' ' modify- entry '

'

, '

' remove -entry' ' (ditto !

)

8-23
o Aliases (e.g., correct resolution, error responses)

o Authentication and Access Control (e.g., limitation of

modify access)

o ROSE** (e.g., correct handling of invokes, results, rejects,

and invoke ids)

o ACSE** (e.g.

,

association establishment / refusal for

invalid application contexts, etc.)

** important for the testing of DUAs

8.18.2 Distributed PSA Mixed Mode Integration Testing

As a natural evolution of the Directory it is likely that some

mixture of DSAs supporting different modes of interaction will

come to being (the modes referred to are referral, chaining, and

multicasting) . Tests applied to mixed mode configuration

interworking are significantly more complex for any single

requested operation. The complexity is a function of the number

of cooperating DSAs supporting many different modes of

interaction.

One possible integration test configuration may be found in the

Directory documents part 4 clause 8.

8.18.3 Search Operation

Testing of support for filter items should be reasonable. It is

not expected that DSAs will be able to handle worst case testing

in this area.

8 , 19 Errors

The contents of this section are in the form of a strawman and should

be completed prior to the final copy of this document going to press.

o busy Error - Temporary

o unwillingToPerform error - Perm,

o We need an unsupported error that is Perm,

o Should provide a table indicating perm / temp nature of

various errors

8-24
8 . 20 APPENDIX A Definitions

Any definitions not found in this appendix can be found in the

Directory Documents.

o Holding

o Propagating

o Stand-alone

o Cooperating

8-25
8.21 APPENDIX B Attributes and Object Classes

The Contents of this section are for further study. Additional work

describing algorithms related to schmas and special attribute types

should be placed here.

The attribute types defined in the Directory documents, par 6, and

listed in tables 8.1 and 8.2 have requirements for underlying

algorithms which relate:

1. To the checking of attribute values from the viewpoint of

syntactical correctness and compliance with pragmatic

constraints

2. To the comparison of attribute values for the purpose of

comparison (for equality, for matching substrings, and as a preliminary for determining relative ordering)

Sections B.2 and B.3 give brief characteristics of the checking and

comparison algorithms, respectively. These characteristics are not

currently defined explicitly in the Directory documents. Section B.4

summarizes there applicability to the attribute syntaxes defined by

the Directory documents

It should be noted that determining relative ordering requires the

application of a further algorithm appropriate to the type of value

which requires ordering.

B „ 1 Checking Algorithms

Note. A particular attribute type in some cases defines more than one

alternative attribute syntax. In this case, an attribute value is

satisfied if it satisfies at least one checking algorithm, as listed

below.

B.1.1 T.61 String Check

Checks that the value has the type code for T.61 string, that it

encodes a sequence of valid T.61 characters, and that it complies with

a maximum character length, if this is specified for this syntax,

B.1.2 Printable String Check

Checks that the value has the type code for Printable String, that it

encodes as a sequence of valid printable string if this is specified

for this syntax.

B.1.3 Numeric String Check

8-26
Checks that the value has the type code for numeric string, that it

encodes a sequence of valid numeric string characters, and that it

complies with a maximum character length, if this is specified for

this syntax.

B.1.4 Distinguished Name Check

Checks that the value is a valid ASN.l encoding for Distinguished

name, and that for each known attribute type (i.e. that is registered

in the DSA) each attribute value satisfies the appropriate checking

algorithm.

B.1.5 Object Identifier Check

Checks that the type is correct. It is further study whether the

value itself can be validated further.

B.1.6 Criteria Check

Checks that the value is a valid ASN.l encoding for Criteria. It is

for further study whether the value itself can be validated further.

B.1.7 Presentation Address Check

Checks that the value is a valid ASN.l encoding for Presentation

Address, and that each field is within the size limits appropriate to

the field.

B . 1 . 8 Telephone Number Check

For further study.

B.1.9 Telex Number Check

For further study.

B.1.10 G3 Non-Basic Parameters Check

Checks that the value is a valid ASN.l encoding for G3 Non-Basic

Parameters

B.1.11 Teletex Non-Basic Parameters Check

Checks that the value is a valid ASN.l encoding for Teletex Non-Basic

Parameters

B . 1 . 12 Integer Check

Checks that the value has integer type, and lies between defined or

default integer values.

8-27
1.13 String List Check

Checks that each component is compliant using T.61 String Check or

Printable String Check.

B.1.14 Presentation Capabilities Check

For further study.

B.1.15 Octet String Check

No checking.

B . 1 . 16 Country Check

For further study.

B.2 Matching Algorithms

Note. Matching algorithms are conveniently defined in terms of a two

step process.

1. Take the checked reference value and the value to be matched, and

reduce them to a canonical (i.e. standard) form (normalization),

if necessary.

2. Carry out the comparison in the specified way (e. g. equality,

substrings or ordering)

Important Note

The brief descriptions below outline the first step. The algorithms

may be replaced, in a particular implementation, by equivalent

procedures

B.2.1 String Match

Ail the specific algorithms below carry out the following basic

normalization: remote leading and trailing spaces; intermediate

multiple spaces become single spaces. For example

’

’ [sp]Time[sp] [sp] Flies [sp] [sp] '

becomes ’ 'Time[sp]Flies' '

B.2. 2 Case Ignore String Match

The basic normalization just described is carried out; in addition

each lower case letter is converted to its upper case form. The ASN.l

value is compared octet by octet, disregarding type. It is possible

in this way to compare, for example, T.61 strings with Printable

Strings

B.2. 3 Case Exact String Match

8-28
As above, but without the lower case to upper case conversion.

B.2.4 ASN.l Match

The ASN.l is converted to a standardized encoding form:

o Constructors are encoded in indefinite form

o Compound primitive values (e.g. constructor octet-strings) are

converted to their simple form (e.g. a primitive octet string)

two ASN.l values may then be compared octet by octet, including the

initial ASN.l type. No matching for substrings or order is possible.

B.2.5 Distinguished Name Match

As for ASN.l match,, except that for each AVA within the distinguished

name, normalization takes place (possibly recursively) in accordance

with the nature of the attribute type.

B.2.6 Country Match

For further study.

B.2.6 Case Ignore String List Match

Each component must match as for Case Ignore String Match.

i B.2.8 Case Exact String List Match

Each component must match as for Case Exact String Match.

B.2.9 Criteria Match

For further study.

B.2.10 Telephone Number Match

For further study.

B.2.11 Telex Number Match

For further study.

B.2.12 Presentation Capabilities Match

For further study.

B.3 Mapping of Attribute Syntax

8-29
The following table maps the attribute syntaxes of Part 6 to the

algorithms described in B,2 and B.3:

Syntax

undefined

caseExactStringSyntax

caseExactStringListSyntax

caselgnoreStringSyntax

Printable String Check

caselgnoreStringListSyntax

numericStringSyntax

printableStringSyntax

distinguishedNameSyntax

obj ectldentifierSyntax

criteriaSyntax

presentationAddressSyntax

telephoneNumberSyntax

te 1 exNumbe rSyntax

g3NonBasicParame terSyntax

teletexNonBasicPar . .

presentationCapabilities . .

countrySuntax

integerSyntax

octetStringSyntax

Check

Name

T.61 String Check or

Printable String Check

String List Check

T.61 String Check or

String List Check

Numeric String Check

Printable String Check

Distinguished Name Check

Object Identifier Check

Criteria Check

Presentation Addr. Check

Telephone Number Check

Telex Number Check

G3 Non-Basic . . . Check

Teletex Non-B . . . Check

Presentation . . . Check

Country Check

Integer Check

Octet String Check

Match

No normalization

Case Exact String Match

CaseExactStringListMatch

Case Ignore String Match

Case Ignore Sting List M

Case Exact String Match

Case Exact String Match

Distinguished Name Match

No normalization

Criteria Match

Presentation Address Mat

Telephone Number Match

Telex Number Match

No normalization

No normalization

Presentation Capabilitie

Country Match

No normalzation

No normalization

8-30
8.22 APPENDIX C The Use of ROSE

The use of ROSE by the BIND and UNBIND macros as described in the

Directory documents, part 5, sections 10.1 and 10.2, will be used with

no additional agreements.

8-31
8.23 APPENDIX D Guidelines

The following guidelines were used to provide a general mechanism for

arriving at pragmatic constraints within the Directory. These are

included for the readers information.

1 . Align with other activities

2 . Catch outlandish behavior

o Infinite Loops

o Runaway Process

3. Conserve Resources and Promote Efficiency

o Memory

o CPU

o Bandwidth

o Effort

4. Compromise Arbitrary Opinions

5. Police Actions / Catch Violators

o Protect the Network

6. Facilitate Interworking

7. Syntax Interpretation

o Errors

8. Set practicle limits for the purpose of testing

8-32
8.24 APPENDIX E Glossary

ACL

ACSE

ADDMD

AETitle

APDU

ASE

ASN.l

AVA

B-RM

CA

CCITT

CEN

CENELEC

CEPT

COS

DAP

DIB

DIT

DMD

DSA

DSP

DUA

FTAM

INTAP

ISDN

ISO

KT

LL

MAP

MHS

NBS

NSAP

OSI

PKCS

POSI

PRDMD

PSAP

RDN

ROSE

SIG

SPAG

TOP

UL

UPU

Access Control List

Association Control Service Element

Administration Directory Management Domain

Application Entity Title

Application Protocol Data Unit

Application Service Element

Abstract Syntax Notation - 1 Attribute Value Assertion

Basic Reference Model

Certification Authority

Consultative Committee on International Telegraph &

Telephone

Committee for European Normalization

Committee for European Normalization Electronique

Committee European Postal & Telephonique

Corporation for Open Systems

Directory Access Protocol

Directory Information Base’

Directory Information Tree

Directory Management Domains

Directory System Agent

Directory System Protocol

Directory User Agent

File Transfer, Access & Management

Industrial Technical Application Profiles

Integrated Services Digital Network

International Organization for Standardization

Knowledge Tree

Lower layers of OSI model (layers 1-4)

Manufacturing Automation Protocol

Message Handling Systems

National Bureau of Standards

Network Services Access Point

Open Systems Interconnection

Public Key Crypto System

Promotion for Open System Interconnection

Private Directory Management Domain

Presentation Service Access Point

Relative Distinguished Name

Remote Operations Service Element

Special Interest Group

Standards Promotion & Application Group

Technical and Office Protocols

Upper layers of OSI model (layers 5-7)

Universal Postal Union

8-33
8.25 APPENDIX F Aliigrunent Errata

To be supplied in December,

8-34
8.26 APPENDIX G Open Issues Related to the Directory Standard

The following issues are concerns or clarifications needed in regard

to the Directory documents. These are not issues which the Directory

SIG may handle itself. Rather, they require changes to the protocol

or other fundamental issues in the Directory documents. This is not

an all inclusive list of issues.

G„1 Issues with Required Interpretations

G . 1 . 1 ASN . 1 Ordering

A Problem has been identified with the ASN.l definition of

' CompareArgument ' and * attributeError ' in the Directory documents Part

3. The problem is that in both these productions the elements

'AttributeType' and ' AttributeValue ' are defined within a SET rather

than within a SEQUENCE. Since 'AttributeValue' is defined as an ASN.l

data type ANY, it can only be -parsed after 'AttributeType' is known

(because the latter determines the ABSTRACT -SYNTAX of the former)

Thus, it becomes quite difficult to parse a PDU containing one of the

above productions if 'AttributeValue' appears before 'AttributeType'.

If this is not changed in the standard these agreements require that

' AttributeType ' must always be encoded before its corresponding

'AttributeValue'

G.1.2 Ordering of Attribute Values

The Directory documents, part 2, define Attribute in terms of a ''SET

of AttributeValue''. This definition permits no significance to be

given to the order of attribute values.

This represents a significant loss of generality. The owner of an

attribute (say, an organization) may wish to imply an order of

preference, or some other meaning, but it is prohibited from doing so.

The solution is to replace ''SET OF'' with ''SEQUENCE OF'', together

(preferably but not essentially) with a means within modify- -entry of

managing the order of the values within the attribute.

In the meantime, implementors are required to maintain order as if the

definition was already ''SEQUENCE OF'', leaving the protocol

definitions as they stand. By doing so, an eventual change can be

accommodated with a minimum of effort.

G . 1 . 3 Name Resolution

In the absence of a stated method of selecting the naming context

whose superior reference is to be used in step 10 of the Name

Resolution, the following algorithm should be used:

8-35
1. Name resolution should use Local References, Subordinate

References or Cross References, as defined in the Directorydocuments, before considering the use of Superior References.

2. In selecting a Superior Reference, the one that corresponds to a naming-context whose context prefix gives the best match to the

purported name should be used (in doing this, naming contexts

that are subordinate to other naming contexts are ignored.)

3. If more than one naming context provides the best match, the

selection between them is a local matter (having regard to

bracketed rule in item 2, above).

4. If no naming context provides even a partial match, the naming

context with the shortest context prefix (i.e. least number of

RDNs) should be selected; if more than one, the selection

between them is a local matter.

G„2 Issues with No Required Interpretations

Issues in this section are listed for the readers information.

Implementors should explicitly not consider these items as

requirements of this agreement.

G.2.1 Substrings

The inability to specify that substrings in a filterltem are to be

anchored to the beginning or end of a string greatly weakens the value

of the facility, while saving nothing in the implementation. The

Directory documents should specify a mechanism for anchoring substring

matches

G.2.2 Association Class 3

The use of Association Class 3 in the DSP protocol has been identified

as desirable. This would allow cooperating DSAs to multiplex chained

operations over a single application association, thus reducing the

overhead and cost associated with the establishment of application

associations

As it currently stands, the DSP protocol does not provide the

necessary support for Association Class 3, namely, the negotiated

release of an application association (a DSA must be able to refuse an

UnBind request)

G.2.3 Service Controls

The following is a brief list of unclear issues related to service

controls

1 . What is the relationship between various service controls and

8-36
security and/or digitally signed results?

2. How does an aboandon operation affect a chained operation; the

abandon operation is not available in the DSP.

G . 2 . 4 Authentication

The following items are issues and concerns related to the

authentication framework which should be noted.

G.2.5 Encryption Algorithm

Currently the Directory only permits the use of one encryption

algorithm; it is desirable that the Directory be able to support

multiple algotithms for the purpose of authentication.

G.2.6 Digital Signatures on Operations

Use of digital signatures on operations currently wraps (encrypts) 3

components; Distinguished Name, Common Arguments, and Service

Controls. This leaves intermediate DSAs unable to modify Service

Controls while retaining the signature. It is desirable that Service

Controls not be wrapped by the digital signature. The collation and

return of relayed partial results can not be accomplished while

retaining the digital signature.

Additionally it is unclear that digitally signed results can be

''unwrapped'' and examined by intermediate DSAs.

8-37
'
9. SECURITY

The Security Architecture specified in ISO 7498/Part 2 - Security

Architecture (as presented in ISO/TC 97/SC 21/N1528) shall be used as a basis for further work in the Special Interest Group on Security.

The security services that are to be implemented first shall include

confidentiality, integrity, authentication and access control. Nonrepudiation of the source shall also be included for consideration for

implementation. These services are defined and discussed in more detail

in ISO 7498/Part 2 - Security Architecture.

9.1 Definitions

The following definitions, based on the definitions in ISO 7498/Part2,

are to be used when interpreting Chapter 9.

Access Control: The provision of a security system

that establishes and enforces which

users or processes can get access

to what data or processing

facilities

Authentication

Information: Information used to establish the

validity of a claimed identity.

Authorization:

Confidentiality:

The granting of access rights.

A security service that protects

data from unauthorized disclosure.

Connection:

Connectionless

Data Integrity:

A state of communication that

exists between two communicating

entities by establishing an

association between them, providing

one or more data paths between them

allowing sequential transfers of

data, and then terminating the

association.

A state of communication that

provides transfer of data from one

entity to another without a preestablished association.

The property that data has not been

altered or destroyed in an

unauthorized manner.

9-1
Data Origin

Authentication;

Digital Signature:

Peer-entity

Authentication:

Repudiation:

Selective Field

Protection:

Traffic Analysis:

Traffic Flow

Confidentiality:

The corroboration that the source

of data received is as claimed.

Data that allows a recipient of

information to verify the source

and integrity of the information.

The corroboration that peer

entities in an association are as

claimed.

Denial by one or both of the

entities of an association of

having participated in all or part

of the association or

communication of the association.

The protection of specified fields

of data in a communication.

The inference of information from

observation of traffic flow in

communications (presence, absence,

amount, direction and frequency).

A confidentiality service to

protect against traffic analysis.

9.2 Matrix of Security Services and OSI Layers

The. following matrix shows the layers of the OSI architecture at which

certain security services are considered to be desirable. The entries

in the matrix are "H" for high level of desirability, "M" for medium

desirability, and "L" for low level of desirability. No entry in the

matrix means that the service is not considered desirable. This

matrix was produced from a similar matrix in ISO 7498/Part 2 which

showed the layers of the architecture that could be used to provide

the security service. The level of desirability was established by

the members of the Special Interest Group in Security of the OSI

Implementors Workshop.

Notes The Matrix is a consensus of the opinions of the members as to

where selected security services should be placed. It should not be

considered restrictive and interpreted as meaning that the security

services cannot be placed elsewhere in the OSI architecture or have

other implementation priorities. This will depend upon the differing

9-2
considered complete in that other security services may exist that

should be incorporated in the architecture.

Table 9.1 OSI Layers Desirable for Placing Security

l.(a)

(b)

SERVICE

Peer entity authentication

Data origin authentication

H

H

2. Access Control Service Authorization Model

3. (a) Connection confidentiality

(b) Connectionless confidentiality

(c) Selective field confidentiality

(d) Traffic flow confidentiality

H

H

H

H

H

H

L

4. (a) Connection integrity with recovery

(b) Connection integrity without recovery

(c) Selective field connection integrity

(d) Connectionless integrity

(e) Selective field connectionless integrity

H

No Plan

No Plan

H L

L

L

H

5. (a) Non-repudiation: originator

(b) Non-repudiation: receiver

L

L

Implementation priority: H (high)

M (medium)

L (Low)

Table 1 ISO 7498/Part 2: Security Addendum -- NBS OSI Workshop

Summary Of SIG-SEC Discussions of Security Service Placement, May,

1987

Notes: The following notes are for explanation of the above matrix and

comments

A security system should be considered to be an integrated set of

security services that are placed at selected OSI layers. The

services should be selected based on a risk analysis for the computer

system being protected. Security mechanisms must be then chosen that

will provide the security services and incorporated in the software

and hardware of the computer system and controlled by the OSI software

and hardware at the selected layer(s)

For example, authentication, access control, confidentiality and

9-3
integrity are selected as the major security goals for an OSI system.

A connection oriented transport protocol is being implemented. An

example of the use of the Matrix could be in an electronic mail

system, to illustrate this the following specific services and layers

were chosen:

Peer entity authentication: Layer 4

Data origin authentication: Layer 7

Access Control: Layer 7

Connection confidentiality: Layer 4

Selective field confidentiality: Layer 7

Connection integrity with recovery: Layer 4

Connectionless integrity: Layer 7

The layer 7 services were chosen to support the mail system that would

protect the selective paragraphs of an electronic message as directed

by the user. A mail system is considered connectionless. Access

control is a function of only layer 7.

The layer 4 services were chosen to provide a reliable transport

service from the sender to the intended receive of the electronic

message. A full connection integrity and confidentiality service with

peer entity authentication will assure that all information gets to

the receiver correctly and confidentially.

Note: The security protocols and mechanisms that provide these

services are beyond the scope of this Chapter at this time. The

mechanisms and standards for their interoperability are presently

being defined and will be added to this Chapter as they become

available

9-4
10 . REFERENCES

Selected references are grouped by organization publishing the documents

and by Reference Model layer to aid the reader in relating standards to

the OSI Basic Reference Model and to aid relating equivalent standards

published by different standards organizations.

10.1 CCITTConsultative Committee for International Telegraph and

Telephone

Network Layer

CCITT Recommendation X.25 - 1984, Interface Between Data Terminal

Equipment (DTE) and Data Circuit-Terminating Equipment (DCE) for

Terminals Operating in the Packet Mode on Public Data Networks.

Transport Layer

CCITT Recommendation X.214, (Red Book, 1984), Transport Service

Definition for Open Systems Interconnection for CCITT Applications.

CCITT Recommendation X.224, (Red Book, 1984), Transport Protocol Profile

for Open Systems Interconnection for CCITT Applications.

Session Layer

CCITT Recommendation X.215, (Red Book, 1984), Session Service Definition

for Open Systems Interconnection for CCITT Applications.

CCITT Recommendation X.225, (Red Book, 1984), Session Protocol Profile

for Open Systems Interconnection for CCITT Applications.

Application Layer -- MHS

CCITT Recommendation X.400, (Red Book, 1984), Message Handling Systems:

System Model-Service Elements.

CCITT Recommendation X.401, (Red Book, 1984), Message Handling Systems:

Basic Service Elements and Optional User Facilities.

CCITT Recommendation X.408, (Red Book, 1984), Message Handling Systems:

Encoded Information Type Conversion Rules.

CCITT Recommendation X.409, (Red Book, 1984), Message Handling Systems:

Presentation Transfer Syntax and Notation.

CCITT Recommendation X.410, (Red Book, 1984), Message Handling Systems:

Remote Operations and Reliable Transfer Server.

CCITT Recommendation X.411, (Red Book, 1984)

,

Message Handling Systems

REF-1
Message Transfer Layer.

CCITT Recommendation X.420, (Red Book, 1984), Message

Handling Systems: Interpersonal Messaging User Agent Layer.

CCITT Recommendation X.430, (Red Book, 1984), Message Handling Systems:

Access Protocol for Teletex Terminals.

CCITT documents may be obtained from:

International Telecommunications Union

Place des Nations, CH 1211,

Geneva 20 SWITZERLAND

10 .EIA: Electronic industries Association

Physical Layer

Interface Between Data Terminal Equipment and Data Communication

Equipment Employing Serial Binary Data Interchange, EIA-232D.

Application Layer

Manufacturing Messaging Service for Bi-directional Transfer of Digitally

Encoded Information, Part 1: Service Specification, RS 511, 1986.

Manufacturing Messaging Service for Bi-directional Transfer of Digitally

Encoded Information, Part 2: Protocol Specification, RS 511, 1986.

10.3 IEEE: Institute of Electrical and Electronic Engineers. Inc*.

Physical Layer

IEEE Standard for Local Area Networks: Carrier Sense Multiple Access

with Collision Detection (CSMA/CD) and Physical Layer Specification,

ANSI/IEEE Standard 802.3 1985, Institute of Electrical and Electronics

Engineers, 345 East 47th St., New York, NY. 10017, 1985.

IEEE Standard for Local Area Networks: Token-Passing Bus Access Method

and Physical Layer Specification, ANSI/IEEE Standard 802.4 - 1985,

Institute of Electrical and Electronics Engineers, 345 East 47th St.,

New York, NY. 10017, 1985.

IEEE Standard for Local Area Networks: Token-Ring Access Method,

REFANSI/IEEE Standard 802.5-1985, Institute of Electrical and Electronics

Engineers, 345 East 47th St., New York, NY. 10017, 1985.

Data Link Layer

IEEE Standard for Local Area Networks: Logical Link Control, ANSI/IEEE

Standard 802.2 - 1985, Institute of Electrical and Electronics Engineers,

345 East 47th St., New York, NY. 10017, 1985.

10 .ISA: Instrumentation Society of America

Instrumentation Society of America: Proway-LAN, ISA-S72.01, 1985.

Proposed Instrumentation Society of America Standard: Process Control

Architecture, dS S72.03, 1987.

10.5 ISO: International Organization for Standardization

Status of ISO work can be determined by the reference number; working

drafts are referenced by committee and number; e.g., TC 97/SC 6 Nxxxx.

Standards are cited by either ISO xxxx or IS xxxx; DIS and DPs are cited

in similar form.

Information Processing Systems - Open Systems Interconnection - Basic

Reference Model. ISO/IS 7498. First Edition - Oct. 15, 1984. Ref. No.

ISO 7498-1984(E)

OSI Basic Reference Model - Part 2: Security Architecture. ISO/TC 97/SC

21/N1528. Project 97.21.18. September 1986.

OSI Basic Reference Model - Part 3: Naming and Addressing. ISO/DIS 7498-

3, ISO/TC 97/ SC 21 N2141. May, 1987.

Data Interchange - Structure for the identification of organizations.

ISO 6523. 1984-02-01.

Data Link Layer

Information Processing Systems - Data Communications - High-Level Data

Link Control Procedures - Description of the X.25 LAPB-compatible DTE

Data Link Procedures, IS 7776.

Network Layer

Information Processing Systems - Open Systems Interconnection - Network

Service Definition, IS 8348.

REFInformation Processing Systems - Open Systems Interconnection - Addendum

to the Network Service Definition Covering Connectionless Data

Transmission, IS 8348/ADI.

Information Processing Systems - Open Systems Interconnection - Addendum

to the Network Service Definition Covering Network Layer Addressing,

IS 8348/AD2

Information Processing Systems - Open Systems Interconnection - Internal

Organization of the Network Layer, DIS 8648.

Information Processing Systems - Open Systems Interconnection - Protocol

for Providing the Connectionless Network Service, IS 8473.

/

Information Processing Systems - Open Systems Interconnection -Addendumto

IS 8473 - Provision of the Underlying Service Assumed by ISO 8473, ISO TC

97/SC 6 N 3453.

Information Processing Systems - Open Systems Interconnection, Working

Draft, End System to Intermediate System Routing Exchange Protocol for

use in Conjunction with ISO 8473 ISO TC 97/SC 6 N 4053.

Information Processing Systems - Open Systems Interconnection - Data

Communication - X.25 Packet Level Protocol for Data Terminal Equipment,

IS 8208.

Transport Layer

Information Processing Systems - Open Systems Interconnection - Transport

Service Definition, IS 8072.

Information Processing Systems - Open Systems Interconnection - Transport

Protocol Profile, IS 8073, 1984.

Session Layer

Information Processing Systems - Open Systems Interconnection - Basic

Connection Oriented Session Service Definition, IS 8326 August 15, 1987.

Information Processing Systems - Open Systems Interconnection - Basic

Connection Oriented Session Protocol Profile, IS 8327. August 15, 1987.

Information Processing Systems - OSI - Basic Oriented Session Service

Definition - DAD 2 to ISO 8326 to Incorporate Unlimited User Data, ISO/IS

8326. Aug. 27, 1987.

Information Processing Systems - OSI - Basic Oriented Session Service

Protocol - DAD 2 to ISO 8327 to Incorporate Unlimited User Data, ISO/IS

8327. Aug. 27, 1987.

Presentation Layer

REF-4
Information Processing Systems - Open Systems Interconnection - Connection-Oriented Presentation Service Definition, DIS 8822 - Revision

C.

Information Processing Systems - Open Systems Interconnection - Connection-Oriented Presentation Protocol Profile, DIS 8823 - Revision C

Information Processing Systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.l). ISO 8824 - 1987-

05-19.

Information Processing Systems - Open Systems Interconnection - Specification of Basic Encoding Rules for Abstract Syntax Notation

(ASN.l), ISO/DIS 8825 - 1987-05-19.

7-bit Coded Character Set for Information Processing Interchange,

ISO-646.

Information Interchange - Representation of Local Time Differentials,

ISO-3307

Application Layer

Application Layer Structure, ISO/DP 9545, ISO/TC97/SC21/N1743 . July 24,

1987.

Application Layer -- FTAM

Information Processing Systems - Open Systems Interconnection - File

Transfer, Access and Management Part I: General Introduction, DIS 8571/1

Information Processing Systems - Open Systems Interconnection - File

Transfer, Access and Management Part II: The Virtual Filestore, DIS

8571/2.

Information Processing Systems - Open Systems Interconnection - File

Transfer, Access and Management Part III: File Service Definition, DIS

8571/3.

Information Processing Systems - Open Systems Interconnection - File

Transfer, Access and Management Part IV: File Protocol Profile, DIS

8571/4.

Application Layer -- ASE/CASE

Information Processing Systems - Open Systems Interconnection - Service

Definition for Common Application Service Elements - Part 2: Association

Control ACSE Editor's Draft #2, 8/27/87.

Information Processing Systems - Open Systems Interconnection - Protocol

Profile for Common Service Elements - Part 2: Association Control, ACSE

REFEditor's IS review d #2, 8/27/87.

Application Layer -- VTP

Information Processing Systems - Open Systems Interconnection - Virtual

Terminal Service - Basic Class, IS 9040.

Information Processing Systems - Open Systems Interconnection - Virtual

Terminal Protocol - Basic Class, IS 9041.

Application Process -- Office Document Interchange -- ODA/ODIF

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format - Part 1 ; General

Information, DIS 8613/1.

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format - Part 2; Document

Structures, DIS 8613/2.

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format -• Part 3; Document

Processing Reference Model, DIS 8613/3.

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format - Part 4; Document

Profile, DIS 8613/4.

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format - Part 5; Office

Document Interchange Format, DIS 8613/5.

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format - Part 6; Character

Content Architecture, DIS 8613/6.

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format - Part 7 ; Raster

Graphics Content Architecture, DP 8316/7.

Information Processing Systems - Text and Office Systems - Office

Document Architecture (ODA) and Interchange Format - Part 8; Geometric

Graphics Content Architecture, DP 8613/8.

Information Processing Systems - Text and Office Systems - Standard

Generalized Markup Language (SGML), IS 8879.

Application Process -- Computer Graphics -- CGM/GKS

Information Processing Systems - Computer Graphics - Metafile (CGM) for

the Storage and Transfer of Picture Description Information, Part 1;

Functional Specification, IS 8632/1

REFInformation Processing Systems - Computer Graphics - Metafile (CGM) for

the Storage and Transfer of Picture Description Information, Part 2;

Character Encoding, IS 8632/2

Information Processing Systems - Computer Graphics - Metafile (CGM) for

the Storage and Transfer of Picture Description Information, Part 3;

Binary Encoding, IS 8632/3.

Information Processing Systems - Computer Graphics - Metafile (CGM) for

the Storage and Transfer of Picture Description Information, Part 4;

Clear Text Encoding, IS 8632/4.

Information Processing Systems - Font and Character Information

Interchange, IS 9541.

Information Processing Systems - 8-Bit Single Byte Coded Graphic

Character Sets, Part 1; Latin Alphabet Part 1, IS 8859/1.

Information Processing Systems - Computer Graphics Functional

Specification of the Graphical Kernel System (GKS) , IS 7942.

Information Processing Systems - Computer Graphics - Graphical Kernel

System for Three Dimensions (GKS-3D) , Functional Description, DIS 8805.

Information Processing Systems - Computer Graphics - Programmers

Hierarchical Interactive Graphics System (PHIGS) , DP 9592.

Information Processing Systems - Computer Graphics - Interfacing

Techniques for Dialogues with Graphical Devices (CGI), ISO TC 97/SC 21 N

1179.

ISO documents may be obtained from:

Frances E . Schrotter

ANSI

ISO TC 97/SC 6 Secretariat

1430 Broadway

New York, NY„ 10018

10.6 MAP

Manufacturing Automation Protocol, General Motors

Corporation, Manufacturing Engineering and Development, Advanced Product

and Manufacturing Engineering Staff (APMES) , APMES A/MD-39, GM Technical

Center, Warren, MI. 48090-9040.

REF10.7 NBS : National Bureau of Standards

Local Area Networks: Baseband Carrier Sense Multiple Access with

Collision Detection Access Method and Physical Layer Profiles and Link

Layer Protocol, FIPS 107, NTIS, U.S. Department of Commerce, 5285 Port

Royal Road, Springfield, VA. 22161.

Interface Between Data Terminal Equipment (DTE) and

DataCircuit-Terminating Equipment (DCE) For Operation With

Packet-Switched Data Communications Networks, FIPS 100, NTIS, U.S.

Department of Commerce, 5285 Port Royal Road, Springfield, VA. 22161.

Implementation Agreements for Open Systems Interconnection Protocols:

NBS Workshop for Implementors of Open Systems Interconnection, National

Bureau of Standards, NBSIR 86-3385-6, Robert Rosenthal, Editor, Revised

July 1987.

Implementation Agreements Among Participants of OSINET, National Bureau

of Standards, Institute for Computer Sciences and Technology, NBSIR

86-3478, 1987.

U. S. Government Open Systems Interconnection Profile (GOSIP)

,

National Bureau of Standards, Institute for Computer Sciences and

Technology, 1987.

NBS documents may be obtained from:

NTIS

U.S. Department of Commerce

5285 Port Royal Road

Springfield, VA. 22161.

or

National Bureau of Standards

Institute for Computer Sciences and Technology

Gaithersburg, MD. 20899

10.8 NCS: National Communications System

Interface Between Data Terminal Equipment (DTE) and Data

Circuit-Terminating Equipment (DCE) For Operation With Packet-Switched

Data Communications Networks, National Communications System, Federal

Standard FED-STD 1041.

REF10.9 TOP

Technical and Office Protocols, Boeing Computer Services, Network

Services Group, P.0. Box 24346, M/S7C-16, Seattle, WA. 98124-0346.

REF -9
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2. Performing Organ. Report No. 3. Publication Date

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4. TITLE AND SUBTITLE

Draft Stable Implementation Agreements for Open Systems Interconnection

Protocols

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