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**REPORT CONCERNING INFORMATION**

**INTERCHANGE PROCESSES**

  -----------------------------------------------------------------------
  **UNIQUE IDENTIFICATION OF CCSDS OBJECTS AND SERVICES**

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**CCSDS A31.0-Y-1**

**YELLOW BOOK**

June 2000

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AUTHORITY

  ---- -------------------- ------------------------------------------ ----
                                                                       

       Issue:               Yellow Book, Issue 1                       

       Date:                June 2000                                  

       Location:            Toulouse, France                           

                                                                       
  ---- -------------------- ------------------------------------------ ----

This document has been approved for publication by the Management
Council of the Consultative Committee for Space Data Systems (CCSDS) and
reflects the consensus of technical panel experts from CCSDS Member
Agencies. The procedure for review and authorisation of CCSDS Reports is
detailed in reference \[1\].

This Recommendation is published and maintained by:

> CCSDS Secretariat
>
> Program Integration Division (Code MT)
>
> National Aeronautics and Space Administration
>
> Washington, DC 20546 USA

FOREWORD

This Report defines the highest-level CCSDS identifiers available to
distinguish among types of CCSDS-defined objects and services at the
CCSDS level, and it describes how to construct unique identifiers in the
larger context of International Organization for Standardization (ISO)
and International Telegraph and Telephone Consultative Committee (CCITT)
identifiers.

This document serves as a resource for CCSDS Panel members as they
develop Recommendations which specify or use unique identifiers.

Through the process of normal evolution, it is expected that expansion,
deletion, or modification of this document may occur. This Report is
therefore subject to CCSDS document management and change control
procedures which are defined in reference \[1\]. Current versions of
CCSDS documents are maintained at the CCSDS Web site:

http://www.ccsds.org

Questions relative to the contents or status of this document should be
addressed to the CCSDS Secretariat at the address indicated on page i.

At time of publication, the active Member and Observer Agencies of the
CCSDS were:

[Member Agencies]{.underline}

-   Agenzia Spaziale Italiana (ASI)/Italy.

-   British National Space Centre (BNSC)/United Kingdom.

-   Canadian Space Agency (CSA)/Canada.

-   Centre National d'Etudes Spatiales (CNES)/France.

-   Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)/Germany.

-   European Space Agency (ESA)/Europe.

-   Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.

-   National Aeronautics and Space Administration (NASA)/USA.

-   National Space Development Agency of Japan (NASDA)/Japan.

-   Russian Space Agency (RSA)/Russian Federation.

[Observer Agencies]{.underline}

-   Austrian Space Agency (ASA)/Austria.

-   Central Research Institute of Machine Building (TsNIIMash)/Russian
    Federation.

-   Centro Tecnico Aeroespacial (CTA)/Brazil.

-   Chinese Academy of Space Technology (CAST)/China.

-   Commonwealth Scientific and Industrial Research Organization
    (CSIRO)/Australia.

-   Communications Research Centre (CRC)/Canada.

-   Communications Research Laboratory (CRL)/Japan.

-   Danish Space Research Institute (DSRI)/Denmark.

-   European Organization for the Exploitation of Meteorological
    Satellites (EUMETSAT)/Europe.

-   European Telecommunications Satellite Organization
    (EUTELSAT)/Europe.

-   Federal Service of Scientific, Technical & Cultural Affairs
    (FSST&CA)/Belgium.

-   Hellenic National Space Committee (HNSC)/Greece.

-   Indian Space Research Organization (ISRO)/India.

-   Institute of Space and Astronautical Science (ISAS)/Japan.

-   Institute of Space Research (IKI)/Russian Federation.

-   KFKI Research Institute for Particle & Nuclear Physics
    (KFKI)/Hungary.

-   MIKOMTEK: CSIR (CSIR)/Republic of South Africa.

-   Korea Aerospace Research Institute (KARI)/Korea.

-   Ministry of Communications (MOC)/Israel.

-   National Oceanic & Atmospheric Administration (NOAA)/USA.

-   National Space Program Office (NSPO)/Taipei.

-   Swedish Space Corporation (SSC)/Sweden.

-   United States Geological Survey (USGS)/USA.

DOCUMENT CONTROL

+------------------+---------------------------+--------+-------------+
| **Document**     | **Title**                 | **     | **Status/** |
|                  |                           | Date** |             |
|                  |                           |        | **Remarks** |
+------------------+---------------------------+--------+-------------+
| CCSDS A31.0-Y-1  | Unique Identification of  | June   | Original    |
|                  |                           | 2000   | Issue       |
|                  | CCSDS Objects and         |        |             |
|                  | Services                  |        |             |
+------------------+---------------------------+--------+-------------+

CONTENTS

[Section]{.underline} [Page]{.underline}

1 INTRODUCTION 1-1

1.1 PURPOSE AND SCOPE 1-1

1.2 DOCUMENT STRUCTURE 1-1

1.3 TERMINOLOGY 1-1

1.4 REFERENCES 1-2

2 UNIQUE IDENTIFIERS 2-1

2.1 CCSDS NAME SPACES 2-2

2.2 ISO/IEC 6523 NAME SPACES 2-3

2.3 ISO 8824 NAME SPACES 2-5

2.4 NAME SPACE SUMMARY 2-6

3 SYNTAX FOR IDENTIFIER EXCHANGES 3-1

Figure

2-1 Example of a Global Identifier Constructed from 2 Name Spaces 2-1

2-2 Name Space Tree 2-7

Table

2-1 CCSDS Highest Level Name Spaces 2-2

2-2 ISO 6523 Identifiers Relevant to Identification of CCSDS Name Spaces
2-3

2-3 ISO 8824 Identifiers Relevant to Identification of CCSDS Under ISO
6523 2-5

# INTRODUCTION

## PURPOSE AND SCOPE

This Report describes the identifiers available to distinguish among
types of CCSDS-defined objects and services at the Consultative
Committee for Space Data Systems CCSDS level, as well as in the larger
context of International Organization for Standardization (ISO) and
International Telegraph and Telephone Consultative Committee (CCITT)
identifiers. It does not provide identifiers for specific objects and
services, as these will be found in other CCSDS Recommendations or are
assigned by other CCSDS services.

This document serves as a resource for CCSDS Panel members as they
develop Recommendations which specify or use unique identifiers. It
enables identifiers for specific CCSDS objects or services to be
recognized as unique in a broader context, up to and including the
general context of ISO and CCITT identifiers.

## DOCUMENT STRUCTURE

Section 2 defines the identifiers that may be used to construct
unambiguous identification within various contexts. Section 3 provides a
recommended syntax for identifier exchange when no other syntax is
preferred.

## TERMINOLOGY

### ACRONYMS

**ADID** - Authority and Description Identifier

**CCITT** - International Telegraph and Telephone Consultative Committee

**CCSDS** - Consultative Committee for Space Data Systems

**ICD** - International Code Designator

**ID** - Identifier

**IEC** - International Electrotechnical Commission

**ISO** - International Organization for Standardization

**JTC1** - Joint Technical Committee One

**OI** - Organization Identifier

**SC** - Subcommittee

### DEFINITIONS

**Identifier**: A character or group of characters constituting a value
which is used to distinguish one entity from another. (Adapted from ISO
6523.)

**Name Space**: A set of unique values which serve as identifiers for a
corresponding set of entities.

## REFERENCES

The following documents are referenced in this Report. At the time of
publication, the editions indicated were valid. All documents are
subject to revision, and users of this Report are encouraged to
investigate the possibility of applying the most recent editions of the
documents indicated below. The CCSDS Secretariat maintains a register of
currently valid CCSDS Reports and Recommendations.

\[1\] *Procedures Manual for the Consultative Committee for Space Data
Systems*, CCSDS A00.0-Y-6. Yellow Book. Issue 6. Washington, D.C.:
CCSDS, May 1994.

\[2\] Standard Formatted Data Units---Control Authority Procedures.
Recommendation for Space Data System Standards, CCSDS 630.0-B-1. Blue
Book. Issue 1. Washington, DC.: CCSDS, June 1993.

\[3\] *Standard Formatted Data Units---Structure and Construction
Rules*, CCSDS 620.0-B-2, Blue Book. Issue 2, November 1996.

\[4\] *Space Link Extension---Service Management Specification*. CCSDS
910.5-R-1, Red Book. Issue 1. December 1999.

\[5\] *ISO/IEC 6523-1:1998 Information technology---Structure for the
identification of organizations and organization parts---Part 1:
Identification of organization identification schemes*, 1998.

\[6\] *ISO/IEC 8824-1:1998 Information technology---Abstract Syntax
Notation One (ASN.1): Specification of basic notation,* 1998.

# UNIQUE IDENTIFIERS

In the development of CCSDS Recommendations, it is sometimes necessary
to define specific identifiers for CCSDS objects or services, or to
define mechanisms by which such identifiers are assigned. These
identifiers are unique within the specified Name Space. For example, the
CCSDS Control Authority Procedures Recommendation (reference \[1\])
establishes a mechanism by which a set of distributed Control Authority
Offices assign identifiers, called Authority and Description Identifiers
(ADIDs), to descriptions of data. Each description is uniquely
identified by its ADID within the Name Space of CCSDS Control Authority
ADIDs.

When information containing identifiers is exchanged between two
entities, it is necessary that they share the same understanding of the
Name Space so that the identifiers remain unambiguous. For example, the
CCSDS Standard Formatted Data Units Recommendation (reference \[3\])
defines a 20-byte label which contains a CCSDS ADID. Any entity which
receives a 20-byte label, and knows how to parse it, will by definition
have an understanding of the ADID Name Space. It will not expect to find
ambiguous identifiers in the ADID field unless a mistake has been made
by the sending entity.

It can happen that two or more Name Spaces need to be combined. This can
occur, for example, with the definition of a service that provides
identifiers from multiple Name Spaces. In this case a more globally
unique identifier may be desired. This is typically constructed by
hierarchically combining the Name Spaces, and then hierarchically
combining the associated identifiers to construct a more global
identifier. One way to express this more global identifier is to
separate the individual identifiers using the \'period\' as shown in the
example of figure 2‑1.

x.y

where:

\'x\' is an identifier from Name Space 1

\'y\' is an identifier from Name Space 2.

Figure 2‑1: Example of a Global Identifier Constructed from Two Name
Spaces

It is not necessary to explicitly identify, for transfer and unambiguous
usage, the fact that \'y\' is an identifier in Name Space 2 when \'x\'
has been defined in Name Space 1 as an identifier of Name Space 2, and
the global identifier is constructed hierarchically. In this case it is
sufficient to give the fact that the first identifier is a member of
Name Space 1. This is the case of hierarchically registered Name Spaces
and hierarchically constructed identifiers, and this is the type of
global identifier that this document addresses. Therefore \'x.y\' is a
unique identifier under Name Space 1 assuming hierarchically registered
Name Spaces.

## CCSDS NAME SPACES

The CCSDS desires to define multiple CCSDS Name Spaces and wishes to
have a unique way to distinguish each Name Space. In this regard CCSDS
acts as the highest level naming authority for the CCSDS domain. An
initial set of CCSDS highest level Name Spaces and their identifiers are
defined in table 2‑1.

Table 2‑1: CCSDS Highest Level Name Spaces

+-------------+--------------------+----------------+-----------------+
| CCSDS Name  | Name Space Title   | Assigning Body | Source for Name |
| Space       |                    |                | Space           |
| Identifier  |                    |                | Definition      |
+-------------+--------------------+----------------+-----------------+
| 1           | Control Authority  | CCSDS in CCSDS | CCSDS 630.0-B-1 |
|             | Procedures         | A31.0-Y-1      | (reference      |
| 2           | Registration       |                | \[2\])          |
|             | Authority          | CCSDS in CCSDS |                 |
| 3           | Identifiers        | A31.0-Y-1      | CCSDS 630.0-B-1 |
|             |                    |                | (reference      |
|             | Control Authority  | CCSDS in CCSDS | \[2\])          |
|             | Procedures         | A31.0-Y-1      |                 |
|             | Authority and      |                | CCSDS 910.5-R-1 |
|             | Description        |                | (reference      |
|             | Identifiers        |                | \[4\])          |
|             |                    |                |                 |
|             | Space Link         |                |                 |
|             | Extension          |                |                 |
|             | Management         |                |                 |
|             | Identifiers        |                |                 |
+-------------+--------------------+----------------+-----------------+

The use of the CCSDS Name Space Identifier provides one way in which to
distinguish these Name Spaces. The definitions of allowed values for
each Name Space are given in the corresponding CCSDS Recommendation. The
issue of syntax for the exchange of identifiers is addressed in section
3. This table will be extended whenever additional CCSDS Name Spaces are
defined.

As an example, consider the string \'2.NSSD0123\' with the information
that it is constructed from hierarchically registered Name Spaces and
that the first identifier is from the CCSDS Name Space. This means that
in the context of CCSDS Name Spaces, the identifier \'2.NSSD0123\' will
be globally unique. Of course within the context of Control Authority
Procedures Authority and Description Identifiers, \'NSSD0123\' is
already globally unique.

## ISO/IEC 6523 NAME SPACES

There may be circumstances when it is useful to use CCSDS Name Spaces in
context with Name Spaces defined outside of CCSDS. The ISO/IEC
6523-1(1998) standard (reference \[5\]) provides a mechanism to
accommodate this requirement. It provides a mechanism to distinguish
organizations, such as CCSDS, which assign identifiers to objects or
services. Under this standard, the British Standards Institute acts as
the registrar for broadly based international organizations. This body
has assigned a number of identifiers to various organizations, including
the ISO itself. The ISO, as an organization that recognizes a variety of
standards bodies, assigns identifiers to such bodies. CCSDS has been
registered as a recognized, international, standards body that also
assigns identifiers. The relevant ISO/IEC 6523 identifiers are provided
in table 2‑2.

Table 2‑2: ISO 6523 Identifiers Relevant to Identification of CCSDS Name
Spaces

+----------+---------------+-------------------+----------+----------+
| Name     | Name Space    | Name Space Type   | A        | Source   |
| Space    | Title         |                   | ssigning | for Name |
|          |               |                   | Body     | Space    |
| Id       |               |                   |          | De       |
| entifier |               |                   |          | finition |
+----------+---------------+-------------------+----------+----------+
| 112      | Standards     | International     | British  | ISO      |
|          | Producing     | Code Designator   | S        | JTC1/SC  |
| 4        | Organization  | (ICD)             | tandards | 32       |
|          | Identifiers   |                   | I        |          |
|          |               | Organization      | nstitute | CCSDS    |
|          | CCSDS Name    | Identifier (OI)   |          | A        |
|          | Space         |                   | ISO      | 31.0-Y-1 |
|          | Identifiers   |                   | J        |          |
|          |               |                   | TC1/SC32 |          |
+----------+---------------+-------------------+----------+----------+

From this table, the CCSDS Name Space has been given an organizational
identifier with a value equal to \'4\' by the ISO JTC1/SC 32 naming
authority. The definition of the allowed values under this Name Space is
given in this document, CCSDS A31.0-Y-1 and, more specifically, in table
2‑1. Further, the Standards Producing Organization Identifiers Name
Space has been given the value \'112\' within the ICD Name Space. The
ICD Name Space is also known as the ISO 6523 Name Space of identified
organizations that also assign their own identifiers.

At the time this document was created, contact information for the
Assigning Bodies in table 2‑2 was as follows:

British Standards Institute - DISC

> 389 Chiswick High Rd
>
> London W4 4AL
>
> Tel: +44 181 996 7466
>
> Fax: +44 181 996 7048

ISO JTC1/SC 32:

> Sophie Clivio
>
> Technical Programme Manager
>
> Standards Department
>
> ISO Central Secretariat
>
> Tel : +41 22 749 72 84
>
> Fax : +41 22 749 73 49
>
> email: clivio@iso.ch

Note that ISO 6523 does not specify an order for the exchange of the
International Code Designator (ICD) and the Organization Identifiers
(OI), nor any other syntactic requirements. Such specifications are
outside the scope of this standard. However, using the \'period\', the
example \'112.4.2.NSSD0123\' together with the information that its Name
Spaces start from an International Code Designator results in a globally
unique identifier under all ICD hierarchically-registered Name Spaces.

## ISO 8824 NAME SPACES

There may be circumstances when it is useful to use ISO 6523 Name Spaces
in context with Name Spaces defined outside of the ISO identification of
registered organizations. The ISO 8824 standard (reference \[6\])
provides a mechanism to accommodate this requirement. It provides a
mechanism, at the ISO level, to distinguish organizations from other
methods by which identifiers might be assigned. In particular it
distinguishes identifier assignments by organizations under ISO 6523
requirements from those in ISO standards. It also distinguishes the ISO
track from other international tracks under organizations such as CCITT.
The relevant ISO 8824 identifiers are provided in table 2‑3.

Table 2‑3: ISO 8824 Identifiers Relevant to Identification of CCSDS
under ISO 6523

+-----------+---------------+------------+-------------+--------------+
| Name      | Name Space    | Name Space | Assigning   | Source for   |
| Space     | Title         | Type       | Body        | Name Space   |
| I         |               |            |             | Definition   |
| dentifier |               |            |             |              |
+-----------+---------------+------------+-------------+--------------+
| 1         | ISO           | ISO and    | ISO and     | ISO 8824     |
|           | Identifiers   | CCITT      | CCITT in    |              |
| 3         |               | I          | ISO 8824    | (reference   |
|           | ISO 6523      | dentifiers |             | \[6\])       |
|           | Organization  |            | ISO in ISO  |              |
|           | Identifiers   | ISO        | 8824        | ISO 6523     |
|           |               | I          |             |              |
|           |               | dentifiers |             | (reference   |
|           |               |            |             | \[5\])       |
+-----------+---------------+------------+-------------+--------------+

From this table, the track in which organizations are assigned
identifiers under ISO 6523 is defined as \'3\'. Further, the ISO track
is distinguished from other tracks (e.g., CCITT or Joint ISO/CCITT) by
the identifier \'1\'. Note that no syntax for the expression of these
identifiers is required by ISO 8824.

However, using the \'period\', the example \'1.3.112.4.2.NSSD0123\'
together with the information that its Name Spaces start from ISO and
CCITT Identifiers results in a globally unique identifier under all ISO
and CCITT hierarchically registered Name Spaces.

## NAME SPACE SUMMARY

The exchange of unique identifiers between 2 parties requires that they
have a common understanding of the Name Space from which the identifier
is taken. When global identifiers are assembled from a set of
hierarchically registered Name Spaces, it is sufficient to identify only
the highest level Name Space involved in order to ensure uniqueness of
the global identifier. At the same time the highest level Name Space
involved is often not the highest level Name Space that could have been
involved, because the exchanging parties will have a common
understanding of a lower level Name Space that is adequate to ensure
uniqueness.

For example, the identifier \'1.3.112.4.2.NSSD0123\' has a highest level
Name Space of \'ISO and CCITT\'. This identifier will be unique among
all \'ISO and CCITT\' identifiers, and it identifies a description whose
ID is \'0123\' registered with the NASA primary Control Authority Office
(ID = \'NSSD\'). However, in all current CCSDS standards it is
sufficient to simply use \'NSSD0123\' as the global identifier, because
the context of usage already establishes that the Name Space in use is
the Control Authority and Procedures---Authority and Description
Identifiers Name Space.

For those cases when a higher level Name Space is needed, this document
provides the information to be used to construct such an identifier from
higher level registered Name Spaces. The available Name Space Tree is
shown in figure 2‑2.

For example, the string 112.4.1.xxx, together with the information that
it starts with the Name Space of the ISO 6523 ICD and is organized
hierarchically, is sufficient to make this identifier unique among all
such identifiers starting with an ICD. In principal, it is possible to
determine that \'112\' identifies Standards Producing Organization
Identifiers, that \'4\' identifies CCSDS Name Space Identifiers
(assigned as the organization identifier by ISO JTC1/SC32 to the CCSDS
authority), that \'1\' identifies Control Authority Procedures
Registration Identifiers (assigned by CCSDS), and that \'xxx\' is
therefore an identifier of a Control Authority Procedures---Registration
Authority, or Control Authority Office as defined in CCSDS 630.0-B-1.

![](media/image3.wmf)

Figure 2‑2: Name Space Tree

# SYNTAX FOR IDENTIFIER EXCHANGES

None of the identifiers discussed so far have an associated syntax for
exchange. There are many possible syntaxes depending on usage. However
as a default, it is recommended that hierarchical order be maintained
and the identifiers be separated by the \'period\'. In addition, the
starting Name Space also needs to be identified to the recipient entity.
The examples, provided in subsection 2.4, conform to this
recommendation. Another example is:

3.112.4.2.NSSD0123

Here the initial Name Space is ISO (\'3\' is assigned within the ISO
Name Space) and it can be determined, in principal, that NSSD0123 is a
Control Authority Procedures---Authority and Description Identifier.
This string provides a unique identifier among all hierarchically
organized strings within the ISO Name Space.