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NBS TECHNICAL NOTE 877

Limil»]^;/:miL lENT OF commerce/ National Bureau of Standards

A Basis for Standardization of

I User-Terminal Protocols

for Computer Network Access
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology,

the Institute for Computer Sciences and Technology, and the Office for Information Programs.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United

States of a complete and consistent system of physical measurement; coordinates that system

with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Measurement Services and the following divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Nuclear

Sciences - —- Applied Radiation - — Quantum Electronics ° — Electromagnetics" — Time

and Frequency " — Laboratory Astrophysics ' — Cryogenics ". THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of well-characterized

materials needed by industry, commerce, educational institutions, and Government; provides

advisory and research services to other Government agencies; and develops, produces, and

distributes standard reference materials. The Institute consists of the Office of Standard

Reference Materials and the following divisions: Analytical Chemistry — Polymers — Metallurgy — Inorganic Materials — Reactor

Radiation — Physical Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to promote

the use of available technology and to facilitate technological innovation in industry and

Government; cooperates with public and private organizations leading to the development of

technological standards (including mandatory safety standards), codes and methods of test; and provides technical advice and services to Government agencies upon request. The Institute consists of a Center for Building Technology and the following divisions and offices: Engineering and Product Standards — Weights and Measures — Invention and Innovation — Product Evaluation Technology — Electronic Technology — Technical Analysis — Measurement Engineering •— Structures, Materials, and Life Safety * — Building

Environment * — Technical Evaluation and Application * — Fire Technology.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides technical services designed to aid Government agencies in improving cost effec- tiveness in the conduct of their programs through the selection, acquisition, and effective

utilization of automatic data processing equipment; and serves as the principal focus within

the executive branch for the development of Federal standards for automatic data processing

equipment, techniques, and computer languages. The Institute consists of the following

divisions: Computer Services — Systems and Software — Computer Systems Engineering — Information Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and

accessibility of scientific information generated within NBS and other agencies of the Federal Government; promotes the development of the National Standard Reference Data System and

a system of information analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services to ensure that the NBS staff has optimum

accessibility to the scientific information of the world. The Office consists of the following

organizational units: Office of Standard Reference Data — Office of Information Activities — Office of Technical

Publications — Library — Office of International Relations.

^Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

^ Part of the Center for Radiation Research.

a I oratpH at Rnillrtpr f^nlnroHr, Rfl'^fO
OF STAIs3/,uQS LIBRARY ^UG 2 6 1975

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l^.^A Basis for Standardization of

IS User-Terminal Protocols for Computer Network Access

\ x^z^rw.-v.vA'.v.>_-- rurtjL^

A. J. Neumann

Systems and Software Division

Institute for Computer Sciences and Technology

National Bureau of Standards

Washington, D.C. 20234

Sponsored by

The National Bureau of Standards Washington, D.C. 20234

and

The National Science Foundation

Office of Science Information Service 1800 G Street, N.W.

Washington, D.C. 20550

.^< °^'^o^

U.S. DEPARTMENT OF COMMERCE, Rogers C. B. Morton, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acfmg Director

Issued July 1975
Library of Congress Catalog Card Number: 75-600052

National Bureau of Standards Technical Note 877

Nat. Bur. Stand, (U.S.), Tech. Note 877, 29 pages (July 1975) CODEN: NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1975

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C13.46:877). Price 80 cents (Add 25 percent additional for other than U,S. mailing).
PREFACE

The Institute for Computer Sciences and Technology of the National

Bureau of Standards (NBS) is developing a basis to begin standardization

of the user protocols for network access to computerized information

systems. With support of the National Science Foundation' s Office of

Science Information Service, a proposal has been completed for a standard interactive protocol to initiate and terminate access to any

computer-based service. This protocol divides the access procedure into

a sequence of specific functional steps, e.g. user identification , authorization , etc. , and defines the occurrence and purpose of user input messages and system output messages.

An initial NBS draft of this proposed protocol was reviewed and

revised during a workshop held at NBS in October 1974. The workshop

participants were selected authorities representing library and information service users, software and service producers, and Federal agencies

supporting major services

Workshop results were summarized in this report, and a draft copy

was circulated to all workshop participants and a few other interested

parties, with requests for comments. Most of the comments received were incorporated in this paper. All comments will be utilized, in further

standardization work. This report documents results as of March 1975.

Protocol standardization could proceed from this basis by refining

the detailed requirements for an intended user group (e.g. Federal

Government agencies) , and subsequently delineating the needed codes,

formats, and options.

Ill
ACKNOWLEDGEMENT

This report represents the combined inputs from a large group of

contributors. Mrs. B. Marron arranged and directed the workshop^

October 30-31, 1974, and contributed to the first working paper discussed at the workshop. Substantive comments regarding the candidate

standard paper were received from P. Atherton, J. L. Bennett, I. Cotton,

M. S. Day, R. H. Giering, R. M. Landau, B. G. Lucas, R. S. Marcus, and

R. Rosenthal. Inputs to this document were received from J. L. Bennett,

C. Gottschalk, J. S. Graber , R. S. Marcus, B. H. Weil, H. White,

and M. E. Williams and are gratefully acknowledged. In addition, credit

is due to all workshop participants who are listed in Appendix 1 of

this report. This study was performed under the technical supervision

of Dennis Fife, Chief of the Computer Science Section.
TABLE OF CONTENTS

Page

Preface m

Acknowledgement iv

Abstract 2

1. Purpose and Scope I

2. Basic Concepts 2

3. Minimum User Protocols 5

4. User and System Commands 7

5. User and System Messages 9

6. Data Elements 15

7. Procedural Options 18

8. Definitions 19

9. References 21

Appendix 1: List of Workshop Attendees 22

A BASIS FOR STANDARDIZATION OF USER-TERMINAL

PROTOCOLS FOR COMPUTER NETWORK ACCESS

J. Neumann

A user-terminal protocol is defined which enables a user

at a terminal to access computerized information systems. The

basic functions such as identification, authorization, and

validation are outlined and various signals and messages making up the protocol are identified. The purpose of the paper

is to establish a basis for standardization and development of

a unified user protocol.

Key Words: Command languages , computers, man-machine systems,

networks, system commands, user protocols.

1. PURPOSE AND SCOPE

This report outlines a user protocol, or access procedure, which

permits a user to access computerized information systems from a data

terminal. "User-Terminal Protocol" or "User Protocol" in the context of

this document, refers to the interaction between a user at a terminal

and a computer system, as needed to initiate or terminate any interactive

or conversational form of computer service.

The scope of procedures defined here is directed at, but not necessarily restricted to, the interactive use of unbuffered keyboard/display

terminal devices, i.e. devices in which depression of a key normally re- sults in immediate transmission of a single character , communicating by

means of the ASCII code, as defined in FIPS Pub 1 (or the American

Standard Code for Information Interchange, American Standard X3. 4-1968)

This paper is a revision and considerable expansion of a draft

reviewed at a workshop held at the National Bureau of Standards on October 30-31, 1974. The changes made by the workshop participants are incorporated in this report. (A list of participants is given in

Appendix 1.)

The original draft included considerable format detail. Since

agreement of functional requirements must precede standardization of

format details, the latter have been omitted and the paper now concentrates on functions performed by the user and the system. In the future,

after consensus has been reached on functional requirements for user protocols, work could proceed towards definition and standardization of

formats, message structures, display symbology , and procedural detail.
This paper is expected to serve as a working proposal and point of

departure for standardization of user protocols for computer-based information systems.

Sections 3 through 8 are written in a format that can be converted

easily into a standard^ document, by omission of the explanatory notes

which are appended to clarify points of disagreement or the rationale

behind procedural features. These notes could be incorporated in an appendix to the standard or in expository remarks accompanying the

approval of the standard.

2. BASIC CONCEPTS

From a user's viewpoint, entry to a computerized information system

consists of a series of user and system actions. The user protocol for

entry begins at the moment a user makes his first contact with the

system, by depressing a key, or turning a switch, and is completed when

he begins an application use of a program, data base, or special purpose

information processing capability.

Several functional phases can be outlined as seen from the user's

viewpoint. The user protocol consists of an entry phase, and an exit

phase. The entry phase consists of the following:

Communications connection

Access request

User identification

Authentication

Service selection

Similarly , the exit phase includes:

Exit request

Display of accounting information

Communications disconnection

Separation into these phases is based on many technical and organizational reasons. Communications connection is usually achieved through

the public telephone system, and is constrained by established procedures, designed primarily for voice communication. Access request is

often implied by calling a dedicated telephone number, connecting to a reserved port or computer entry channel. User identification, authentication and service selection are determined by individual service

organization practices.
The present degree of standardization differs for the various

phases. Communications connection is comparatively well standardized,

and rather uniform procedures, directories, and facilities exist—worldwide—for the telephone plant. As far as terminals are concerned, there

exists a profusion of equipments, with varying capabilities. Although

there are compatible sets of standard codes available fl] , [2] , not all

manufacturers follow the standard, and implementations of the standard

code vary in subsets of the standard code. Terminal capability thus

affects user protocols.

Similarly, implementations of the protocol functions differ, both

as to content and form [3], [4] . Communications procedures are not con- sidered further as subjects for standardization here, except as they may

affect the other functions described.

A spectrum of possible procedures can be envisioned to accommodate

the wide variety of computer service users. Two cases are considered in

this paper: an interactive procedure; and, a simplified, terse procedure. The interactive procedure (see pages 5 and 6) is relatively

easy to use, provides step-by-step guidance to a user, and leads him to

the desired result by appropriate system responses to user entries. The

terse procedure (see page 6) requires less time at the terminal, but

taxes the user's capability and requires more training.

2.1 Impact of Emerging Technology

Some of the user protocols, especially those used in connection

with computer networks, can be quite complex and difficult to use for

the casual user. Additional automation of the user protocol may help to

unburden the user. As an example, entry of a machine readable card into

a terminal reader may provide user identification, possibly a service

request, and other data required to provide service. Such implementation may require additional procedural standards, which though they are beyond the scope of this discussion, should be taken into account in

subsequent standardization or user protocols.

2.2 The User

User protocols need to be designed and standardized for a wide

variety of people. Presently, terminal access to a great extent is the

prerogative of computer specialists or specially trained operators of

terminals in airline reservation, banking, and retailing systems. For

interactive information systems, it is envisioned that a general type of

user who is not a computer professional will have access to these

systems. The access procedure therefore, must be simple, easily learned,

and easily understood.
2.3 The System and System Levels

The user will have access to a keyboard, similar to a typewriter

keyboard, and to a display, either characters printed on a typewriterlike device, or shown on a cathode ray screen.

The terminal user knows little if anything about the various levels

of communications switching , such as the local office, regional or area switching centers, and similarly knows little about the computer hardware, and the various levels of software which provide service to him.

He finds it difficult to distinguish between communications handling

software, operating systems, applications programs, and data base management systems while working at the terminal. Often different signals or

commands are required by different levels of software , and system reac- tions by these levels vary for functions which appear identical to the

user. Often no distinction is made between these levels by the user,

although some general provisions must be made to permit user-controlled

change of level during service operation. The user should not have to

consider levels during the entry or exit procedure.

"System," in the context of this paper, refers to all hardware,

software and procedures supporting the operation of the entry keyboard

and the output display. The "system" is invisible to the user, and the

only means of interaction between user and system are the keyboard and

the display.

2.4 Security and Privacy

In the context of this document, we consider providing aids to the user in order to facilitate his access to the system. We must realize,

however, that this may introduce the issue of security and privacy:

providing aid to the user may also facilitate illegal entry to the

system.

In a large number of systems such as automated library systems,

these issues play a minor role. In many data or information systems,

security and privacy requirements play a major role, and standardization

of user protocols for these systems must take them into account. In

addition, current development in hardware, software and procedures in

connection with data protection and privacy will affect user protocols,

and must be considered in standardization.
3. MINIMUM USER PROTOCOLS

Minimum protocols are defined to be the entry procedure and the

exit procedure . These two procedures are outlined in tables 1, 2, and 3,

and are explained further below. Note that the heavy outlined boxes in

these tables describe those protocols which are candidates for standardization. Related procedures shown outside of these boxes, need to be

recognized, but are not considered for standardization themselves at

this time.

COMMUNICATIONS CONNECTION VERIFICATION (Not part of entry

procedure)

USER ACCESS REQUEST (Not part of entry procedure)

User sends access request

SYSTEM ACKNOWLEDGEMENT

System receives access request (5.1)*

System sends system identification message (5.2)

System sends identification request (5.3)

USER IDENTIFICATION

User receives identification request (5.3)

User sends identification message (5.4)

VALIDATION (5.5)

USER AUTHENTICATION (Optional)

System requests authentication message (Password)

(5.6)

User receives authentication (Password) request

User sends authentication message (Password) (5.7)

SYSTEM SENDS AUTHORIZATION MESSAGE (5.8)

SYSTEM SENDS OPERATIONAL STATUS MESSAGE (Optional) (5.9)

USER SERVICE SELECTION (May be implicit) (5.10)

SERVICE OPERATION (Not part of entry procedure)

* Reference numbers point to message detail in section 5.

Table 1. Entry Procedure
USER OPERATES SYSTEM, decides to Stop (Not part of exit

procedure)

User sends exit request (not part of exit procedure)

EXIT REQUEST

System receives exit request

System processes accounting data

System sends accounting message (5.15)

System sends end message (5.16)

COMMUNICATIONS DISCONNECTION (Not part of exit procedure)

Table 2. Exit Procedure

Hardware Connection Verification

User sends access request (Not part of entry procedure)

SYSTEM ACKNOWLEDGEMENT

System receives access request (5.1)

System sends system identification message (implying user

identification and password as next user steps) (5.2)

USER ENTRY

User sends: User Identification, Password, Service

Selection Message (5.4-, 5.7, 5.10)

System sends operational status message (implying

authorization (5.9)

Service operation (Not part of entry procedure)

Table 3. Abbreviated (terse) Entry Procedure
4. USER AND SYSTEM COMMANDS

The following control signals and commands (this section) and

messages (Section 5) form the detailed access procedures outlined in

tables 1, 2, and 3.

4.1 Special Control Signals

Two types of unique messages occur frequently in access procedures

and receive special attention: the user signal and the system signal. [5]

Each user message is ended with a user signal.

Each system message is followed by a system signal.

4.1.1 User Signal. This signal is generated by the terminal user;

it indicates that an immediate task of data or command entry has been

completed, and that the user is waiting for system action.

Code*: CARRIAGE RETURN or NEW LINE**

4.1.2 System Signal. This signal is generated by a computer, or

a processor and indicates to the terminal user that the immediate

processing task is completed , and that the next action is up to the user.

Code: CARRIAGE RETURN or LINE FEED and COLON**

Note: In an instructional, or verbose mode, an additional request

to the user may be desirable such as: "USER:", "READY:",

"TYPE", etc.

4.2 Restart

This signal is used by the user to reinitiate the entry procedure,

for any reason.

Code: BELL (BEL)

Note: Restarting or interrupting a specific operation once initiated is now regularly done by the BREAK signal, which however

is not provided for in the ASCII code. This is an important

and often used function, and further investigation is needed.

A special "restart" key may need to be recommended to keyboard designers and standardizing agencies.

* Code refers to the ASCII Character Code Designations.

** Implementation depends on terminal capabilities and communication

modes. Several different options need to be determined.

7
4.3 Literal

This signal, when preceding control characters or control signals

eliminates the control significance , and causes the character following

the literal prefix to lose its special significance.

Code: SUBSTITUTE (SUB) Also: CONTROL-Z

Note: A literal convention is also needed for character strings.

The double quotation mark has been recommended for this use.

4.4 Word Separator

This signal is used to separate command words or data elements in

the abbreviated access procedure.

Code: COMMA

Note: A strong case can be made to use the space character as a separation device. It is in almost universal use now in

interactive systems. One difficulty with this is that it

cannot be seen; this difficulty is reduced if the input

device has a reasonably good type-position indication.

Further discussion is needed to resolve this.

4.5 Delete Commands

These commands are used by the user to delete portions of the

access procedure messages.

4.5.1 Delete Last Character Entered (Delete Character) . This

command deletes the last character entered by the user, and frees the

character position for a new character entry. In the case of a literal,

it deletes both the character and the literal prefix.

Code: DELETE (DEL)

4.5.2 Delete. This command deletes all characters entered by

the user on the current line.

Code: CANCEL (CAN) Also: CONTROL-X
5. USER AND SYSTEM MESSAGES

The following standard messages are part of the access procedures

outlined in tables 1, 2, and 3.

5.1 User Access Request (Not part of entry procedure)

This is implied by a user calling a computer access number and

receiving a communications signal indicating establishment of terminalcomputer communications.

Note: In addition, as a result of the access request, certain user

specified format conventions must be established, and terminal attributes must be recognized by the processor , before

communications between the user at the terminal and the

system can be effected. This may be done by automatic

interrogation of the terminal, or by entry of format codes

and terminal attribute codes by the user.

There are many other variants of generating a user access request,

depending on hardware and software factors. The system should acknowledge

completion of the communications connection process, which is done by the

system identification message. This message from the system to the user

is the first message of the access procedure, and serves as a system

acknowledgemen

.

5.2 System Identification Message

Upon receipt of the access request, the system sends a message to

the terminal which indicates the operability of the system, and which

furnishes some basic system identification to the user. The message

contains the following data elements:

Administrative Code (Optional)

Date (Optional)

Port Connection (Optional)

System Name

Time (Optional)

Note: There is agreement on system name as the basic ingredient

of this message. Other elements listed are optional, and

may be omitted in the interest of brevity. The port con- nection may be useful in tracing of communications errors.

It may be expressed in the form of a telephone number or a port number.
5.3 Identification Request

Immediately following the system identification message, the system

sends the identification request to the user. The message has one of the

following forms:

"PLEASE ENTER USER IDENTIFICATION" * "PLEASE ENTER USER ID"

"PLEASE ENTER ID"

"ID"

Note: There are divergent opinions on the desirability of the

various forms shown above. The first long form, normal

language, is the most understandable. The last form is

highly abbreviated and would require a more experienced

user. Some options should probably be allowed to provide

for the explicit and abbreviated forms. Each identification

request is followed by a system signal.

5.4 Identification Message

This message is sent by the user in response to the identification

request (section 5.3). It consists of a string of characters generated

at the keyboard which serves to identify the user, primarily for accounting and billing purposes.

Note: The length of the string will usually be limited, but within

the restricted length, any ID code will be acceptable.

Fields of the user identification code may be subdivided in

subfields reserved for user name, user number, organizational

unit code, etc. These data are used for administrative

statistical and billing purposes.

5.5 Validation

The system receives and analyzes the user identification for acceptability. If acceptable, the access procedure continues to the password

request (section 5.6). If unacceptable, the access procedure provides an error message (sections 5 .11 and 5.13).

* Messages or message elements enclosed in quotation marks are to be displayed literally as shown. Data element names are shown in lower case. Implementation of a displayed message is dependent on availability of

upper and lower case characters, and is not considered for standardization at this time.

10
5.6 Password Request

A password is the most common form used for authentication by the

system. A password is assigned to an individual authorized user by

administrative procedure. It is the final key to entry into the system.

The password is protected against misuse by overprinting, underprinting

or non printing to prevent a reader of hard copy, or an observer of a visual screen from unauthorized knowledge emd possible misuse of a password. After validation, the system sends a password request to the user terminal as follows:

"PLEASE ENTER PASSWORD" or

"PASSWORD" or

"PW"

5.7 Password Message

The user enters the password, which consists of a string of keyboard enterable characters, i.e. any ASCII characters including blank

characters, control characters and user signals if preceded by the

literal prefix.

5.8 Authorization

The system receives and analyzes the password for acceptability.

If acceptable, the access procedure continues to the operational status

message (section 5.9), receipt of which by the user implies to him that

he now is authorized to proceed with service selection. If the password

is not accepted , the access procedure provides an error message (section

5.12)

5.9 Operational Status Message

Password acceptance is immediately followed by the operational

status message which furnishes the latest information on the operating

status of the system. This will be in clear text and may contain such

items as: planned system down time, special scheduled operating hours,

unavailability of some system components, and a telephone number for

user assistance.

5.10 User Service Selection

After receipt of the status message, the user is free to select

the service by the method unique to the particular service being accessed.

This procedure is outside of the access procedure considered in this

document.

11
5.11 User Identification Error

If an error is made or time out elapses during the user identification entry, the system will allow two additional attempts to enter an acceptable user identification , through the following message:

"INVALID USER ID, PLEASE REENTER ID"

5.12 User Password Error

If an error is made in password entry, the system will allow two

additional attempts to enter an acceptable password, through the following message:

"INVALID PASSWORD, PLEASE REENTER PASSWORD"

5.13 Entry Error Shutdown Message

Upon receipt of the third entry or after three minutes of inaction,

either during user identification, or password entry, the system denies

service, and sends the following message to the user:

"INVALID ENTRY, PLEASE CALL YOUR SYSTEM REPRESENTATIVE

FOR HELP"

or

"INVALID ENTRY, PLEASE CALL (nnn) nnn-nnnn"

where the string of "n" characters denotes the service telephone number.

Note: In most systems today, the third invalid entry causes

automatic disconnect.

5.14 Exit Request (Not part of access procedure)

This message indicates to the system that the user desires to

terminate the session.

Note: The exit request message is unique to the particular service system used and varies among systems. At this time, it

is not considered part of the access procedure.

12
5.15 Accounting Message

Upon receipt of the exit request, the system provides the accounting message to the user. It contains the following data elements

DATE

TIME SESSION STARTED

TIME SESSION ENDED

ELAPSED CLOCK TIME

SYSTEM NAME

ADMINISTRATIVE CODE

In addition , a brief statement will be furnished which will inform

the user of units of resources expended in the session, from system

entry to system exit. This may be in terms of dollars and cents,

resource units, connect time, etc.

Note: There is some agreement on the need for the six data elements listed above. Systems use different charging algorithms

and therefore , report usage differently. Some system representatives feel that it is not necessary to report this item.

Some agreement on usage units and need for reporting will be

needed before this can be standardized.

5.16 End Message

End of the session is indicated by the system displaying the

message:

"END"

Note: This is usually appended to the accounting message.

5.17 System Termination

If it should become necessary to terminate the session from the

system side, the user will be informed as follows:

"SYSTEM TERMINATION"

DATE

TIME

SYSTEM NAME

CAUSE OF TERMINATION

. "END"

13
5.18 Irregular User Termination

A user may purposely or inadvertently make a communications disconnection (see table 2.) while operating the system. When the system

detects this event, it will close the interactive session. Upon reentry

the user will receive the following message:

"IRREGULAR TERMINATION"

DATE, TIME, SYSTEM NAME and "END" will be shown as in 5.17 above.

Note: . The system should be designed to facilitate recovery and to

permit user to continue work from the state at which termination

occurred.

14
6. DATA ELEMENTS

Data elements , which are the components of user and system messages,

are listed in this section.

Note: Details of format are dependent on terminal hardware

characteristics , software implementation and codes of

existing systems, and other factors. At this time, it

is important to determine format standards. Data elements appearing in the previous section are listed, and

some of the constraints are noted.

6.1 User Identification

User identification is required for system access control, accounting and statistical purposes.

Several format options exist, such as fixed length or variable

length fields. In variable length codes, a maximum field size may need

to be specified. All alphanumeric characters appearing on the keyboard

should be permitted in user identification. It may be desirable to

allow subfields for user name, user number, organization code, or other

administrative classifications

6.2 Password

The password is required for system access, for authentication of

user access. It should be protected from unauthorized use by underprinting, overprinting, or by non-printing or nondisplaying

6.3 System Name

A system name is an optional feature of the system identification

message. This would be a designation coined by the system owner. It

should uniquely identify the system to be accessed.

Note: Standardization of this item would be concerned with format,

and appropriateness of acronyms or abbreviations . In case of duplication or similarity of system names, some coordinating procedures and ground rules would have to be

established.

6.4 Administrative Code'

This code permits identification of an organization entity, such

as a department, a section, or a division of an organization. It is

used for billing, bookkeeping, or other statistical purposes.

15
6.5 Calendar Date

An all numeric date should be written in the following order:

year-month-day

nnnn-nn-nn

where "n" designates Arabic numerals.

A hyphen should be used as a separator.

The year should be represented by four digits to clearly indicate

the descending order. A two-digit representation for the year is

optional when no confusion can arise from the omission of the century

(see ISO R2014)

Note: Calendar date has been subject to National , Federal and

International standardization. ISO Recommendation R2014

deals with writing of calendar date in all numeric form.

ANSI X3.30 deals with representations for calendar date,

when used for interchange of data among data systems.

The standard was not designed for (nor does it preclude)

usage by humans as input to or output from data systems.

ISO 2711 deals with representation of ordinal dates for

information processing interchange. Federal Information

Processing Standard FIPS 4 (Calendar Date) is prescribed

for interchange of formatted machine sensible coded data

between and among agencies of the Federal Government.

6 . 6 Time

Time of the day is to be represented by the sequence: hourminute-second in the following formats:

h m s

nn:nn:nn

Hours will be indicated in the 24 hour system (i.e. from 00:00:00

through 23:59:59)

Interval time will be indicated in the sequence:

days : hours : minutes : seconds

using the abbreviations "days" , "hrs", "min" , "sec", if required.

Fractions of a second will be expressed in tenths, or hundredths

of a second , as for example : 1:12:15:05.8 . 16
70.1 time elements will be separated by a colon. Decimal fractions

of a second will be indicated by a decimal point.

6.7 Time Zone

For national network operations , the time zone should be indicated

as a three-character code immediately following the time designation.

Example: 13:45: 08EST

For international network operations r Greenwich Mean Time will be

used, followed by the international zone designator Z.

Example: 13:40:16Z

17
7. PROCEDURAL OPTIONS

At least two options should be available to a user for system

access: an interactive option, or instructional version, where each

user step is elicited by explicit instructions from the system; and an abbreviated option which requires only one user entry of all required

data.

The outlines in tables 1 and 2 illustrate the interactive version.

An abbreviated version is outlined in table 3.

Note: It is not clear at this time that a completely interactive

access procedure would be required to access an interactive

information system. The automatic, world-wide telephone

system provides an example of a universal , standardized

method, where a customer dials in sequence an overseas

operator code, a country code, an area code, a city code,

and a local number.

An interactive access procedure may be useful as an instructional

device, or as an option for the casual user. An abbreviated access

procedure may well be preferred by the regular user of an interactive

information system.

The interactive version should be designed to be easy to use for

an inexperienced user; the abbreviated, or terse version should be designed for the convenience of the experienced user. These two modes

need not be mutually exclusive; to help the new user become experienced

and more proficient, the system should permit and encourage a gradual

transition from one extreme to the other, at the user's discretion.

18
8 . DEFINITIONS

Access Procedure - The method of permitting a terminal user to initiate

and terminate operation and use of a computer-based service.

Accounting Message - A message, usually sent to the user at the end of a terminal session, furnishing detail on resources expended

during that session.

Acknowl edgment - A message indicating to the user that the system is

operational

Authentication - The process of verification of user identification.

Authorization - The process of permitting access to the service.

Conversational - Pertaining to a mode of processing, that involves stepby-step interaction between the user at a terminal and a computer, by means of keyboard and display.

Entry Procedure - Part of the access procedure , which permits a user to

operate a computer-based service.

Error Message - A system message indicating the nature of a fault, and

often the remedial action to be taken by the user.

Exit Procedure - Part of the access procedure, which permits a user to

terminate a computer-based service.

Identification - (1) The process of providing personal, equipment, or organizational characteristics or codes to gain access to

computer services, programs , or data. (2) the process of

determining personal , equipment , or organizational characteristics or codes to permit access.

Interactive - Pertaining to exchange of information and control between

a user and the terminal and processor.

Password - A word or string of characters that is recognizable by

automatic means and that permits a user access to protected

storage files, or input or output devices.

Privacy - The right of an individual to control information about himself.

Protocol - A formal set of conventions governing the format and relative

timing of message exchange between the user and the system.

System Message - A message or request from the system to the user.

19
System Security - The totality of measures taken to protect a system from

unauthorized access, accidental or willful interference with

normal operations, or destruction.

System Signal - A message generated by a computer, that indicates to the

terminal user, that an immediate processing task is completed,

and that the next action is up to the user.

Terminal - A device that permits data input into or data output from a computer system, e.g. a teletypewriter, a cathode ray tube

and keyboard device, etc.

User ~ A terminal operator who may be a functional specialist or manager,

and is not assumed to have computer or programming background.

User Command - A brief operational user message.

User Identification Message - A message entered by the user, which is

used to obtain accounting data, and which is also used to

permit access to the system.

User Message - A message from the user to the system.

User Number - A number assigned to a user, which is used as part of the

identification process.

User Signal - A user command, indicating to the system that user entry

of data has been completed.

20
REFERENCES

1. USA Standard Code for Information Interchange, X-3.4-

1968, United States of America Standards Institute

(Federal Information Processing Standard Publication 1,

November 1968)

2. 7-Bit Coded Character Set for Information Processing

Interchange, ISO 646-1973 , International Organization

for Standardization.

3. Dolotta, T. A., Functional Specifications for TypewriterLike Time-Sharing Terminals, Computing Surveys, Vol. 2,

No. 1, March 1970, pp 5 , 31 references.

4. Neumann, A. J., User Procedures Standardization for

Network Access, National Bureau of Standards, Technical

Note 799, October 1973, 10 references.

5. Little, J. L. and Mooers , C. N. Standards for User

Procedures and Data Formats in Automated Information

Systems and Networks. Proceedings of the Spring Joint

Computer Conference. 1968. pp 89-94, 4 references.

21
List of Attendees

Access Procedures Workshop

National Bureau of Standards

October 30-31, 1974

APPENDIX 1

Ms. Pauline Atherton

Syracuse University

Syracuse, New York 13210

Mr. R. W. Bemer

Honeywell Information Systems

P.O. Box 6000

Phoenix, Arizona 85005

Mr. John L. Bennett

Institute for Communication Research

Stanford University

Stanford, California 94304

Mr. Donald Black

System Development Corp.

2500 Colorado Avenue

Santa Monica, California 90406

Mr. Robert Blanc

National Bureau of Standards

Room B-212, Building 225

Washington, D.C. 20234

Dr. Dennis K. Branstad

National Bureau of Standards

Room A-265, Building 225

Washington, D.C. 20234

Dr. Martha Branstad

National Security Agency, Pi

Fort Meade, Maryland 20755

Dr. Lee Burchinall

Chief, Office of Science Information

Service

National Science Foundation

1800 G Street, N.W.

Washington, D.C. 20550

Mrs. Elizabeth Fong

National Bureau of Standards

Room A-265, Building 225

Washington, D. C. 20234

22

Mr. Bill J. Funderburk

System Development Corp.

2500 Colorado Avenue

Santa Monica, California 90406

Mr. Richard Giering

Mead Technology Laboratories

Research Park

Dayton, Ohio 45432

Mr. Charles Gottschalk

Office of Information Services

Al-5210 Century XXI

U.S. Atomic Energy Commission

Washington, D.C. 20545

Mr. James Graber

MARC Development Office

Library of Congress

Washington, D.C. 20540

Mr. Mike Kelly

Informatics, Inc.

6000 Executive Boulevard

Rockville, Maryland 20852

Mr. Richard Krohn

Battelle Columbus Laboratories

505 King Avenue

Columbus, Ohio 43201

Mr. Robert Landau

Science Information Association

3514 Plyers Mill Road

Kensington, Maryland 20785

Mr. Richard Lee

Office of Science Information

Service

National Science Foundation

1800 G Street, N.W.

Washington, D. C. 20550
Mr. Philip Long

State University of New York

Central Administration

Computer Systems Development

99 Washington Avenue

Albany, New York 12210

Dr. Richard Marcus

Project Intrex 35-406

Massachusetts Institute of Technology

Cambridge, Massachusetts 02139

Dr. Edgar Sibley

Department of Information System

Management

University of Maryland

College Park, Maryland 20742

Mr. Martin Snyderman

Smithsonian Science Information

Exchange

1730 M Street, N.W.

Washington, D.C. 20034

Mrs. Beatrice Marron National Bureau of Standards

Room A-265, Building 225

Washington, D.C. 20234

Mr. Larry Stevens

Tymshare, Inc.

11900 Parklawn Drive

Rockville, Maryland 20852

Dr. Thomas H. Martin

Annenberg School of Communications

University of Southern California

915 West 37 Place

Los Angeles, California 90007

Dr. John Murdock

Manager, Information Systems Section

Battelle Columbus Laboratories

505 King Avenue

Columbus, Ohio 43201

Mr. Albrecht J. Neumann

National Bureau of Standards

Room A-157 , Building 225

Washington, D.C. 20234

Dr. Roger Summit

Lockheed Palo Alto Research

Laboratory

Palo Alto, California 94304

Mr. Bill Thompson

Defense Documentation Center

Cameron Station

Alexandria, Virginia 22314

Mr. M. Zane Thornton

Deputy Director

Institute for Computer Sciences

and Technology

National Bureau of Standards

Washington, D.C. 20234

Mr. Robert Reecer

Information Systems Office

Library of Congress

Washington, D.C. 20540

Mr. Ben Weil

Exxon Research & Engineering Co.

P.O. Box 121

Linden, New Jersey 07036

Mr. Robert Rosenthal

National Bureau of Standards

Room B-212 , Building 225

Washington, D.C. 20234

Professor Hasan H. Sayani

Department of Information System

Management

University of Maryland

College Park, Maryland 20742

Mr. Harry White

Associate Director for ADP Standards

Institute for Computer Sciences

and Technology

National Bureau of Standards

Room B-226, Building 225

Washington, D. C. 20234

Ms. Martha Williams

Coordinated Science Laboratory

University of Illinois at

Urbana-Champaign

Urbana, Illinois 61801

23
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBS TN-877

2. Gov't Accession

No.

4. TITLE AND SUBTITLE

A Basis for Standardization of User-Terminal Protocols for

Computer Network Access

3. Recipient's Acces.sion No

5. Publication Date July 1975

6. Performing Organization C

7. AUTHOR(S)

A. J. Neumann

8. Performing Organ. Report

9, PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit ^

11. Contract/Grant No. NSF CA 68

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

National Science Foundation

Office of Science Information Service

1800 G Street, N.W.

Washington, D. C. 20550

13. Type of Report & Period

Covered

14. Sponsoring Agency Code

NSF

15. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 75-600052

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

A user-terminal protocol is defined which enables a user at a terminal to access

computerized information systems. The basic functions such as identification,

authorization, and validation are outlined and various signals and messages

making up the protocol are identified. The purpose of the paper is to establish

a basis for standardization and development of a unified user protocol.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Command languages, computers , man-machine systems, networks, system

commands, user protocols

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I For Official Distribution. Do Not Release to NTIS

I X ' Order From Sup. of Doc, U.S. Government Printing Office ^~ Washington, D.C. 20402. SD Cat. " No. Ci; "-- 46:8^^ }^^^ ^

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