ISO 15888:2000 宇宙データおよび情報転送システム—標準フォーマットのデータユニット—参照環境 | ページ 2

1.1 目的と範囲

この勧告の目的は、多くの有効な CCSDS 参照環境を定義して、オープン システムのデータ交換を促進することです。各参照環境は、これらの各環境内で外部オブジェクトを参照するための構文仕様に関して定義されます。

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.

Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

International Standard ISO 15888 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as CCSDS 622.0-B-1, May 1997) and was adopted (without modifications except those stated in clause 2 of this International Standard) by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 13, Space data and information transfer systems.

1 Scope

This International Standard specifies the requirements for referencing environments for standard formatted data units for space data and information transfer systems.

1 INTRODUCTION

1.2 APPLICABILITY

This Recommendation applies to the use of Standard Formatted Data Unit (SFDU) Replacement Service Objects, i.e. Label Value Objects (LVOs) with Class ID = R. The use of CCSDS Referencing Environments within these objects is required for open system data interchange.

1.3 RATIONALE

The Consultative Committee for Space Data Systems (CCSDS) defined the SFDU concept for the implementation of standard data structures to be used for the interchange of data within and among space agencies. The format of these objects are defined in the SFDU — Structure and Construction Rules Recommendation (Reference [1]).

When SFDU products are generated that reference data objects that are not located in the immediate sequence of octets, they make use of Replacement Service Objects, i.e., Label Value Objects with Class ID = R. The CCSDS realizes it is essential to have at least a small number of well known referencing environments defined to support open system data interchange.

1.4 DOCUMENT STRUCTURE

This document is structured as follows:

A proper understanding of this document requires familiarity with the SFDU concept, the Parameter Value Language (PVL) used to construct statements, and the specific terminology used in this document. If the reader does not have this familiarity, it is recommended that the documents identified in Annex B — Informative References List be read prior to reading this Recommendation. Users may also find it useful to peruse the documents listed in 1.6. This reference list contains documents whose provisions are required for implementing this Recommendation. Annex C — Referencing Environment Tutorial — will be useful to users and implementers of this specification.

1.5 DEFINITIONS

1.5.1 TERMS

For the purposes of this document, the following definitions apply.

Authority and Description Identifier (ADID): The concatenation of the Control Authority Identifier (CAID) and the Data Description Identifier (DDID).

Control Authority (CA): An organization under the auspices of CCSDS which supports the transfer and usage of SFDUs by providing operational services of registration, archiving and dissemination of data descriptions. It comprises:

• a) The CCSDS Secretariat supported by the Control Authority Agent (CA Agent); and
• b) Member Agency Control Authority Offices (MACAOs).

Control Authority Identifier (CAID): A four character restricted ASCII string that identifies an individual Member Agency Control Authority Office (MACAO) or the CCSDS Secretariat.

Data Description Identifier (DDID): A four character restricted ASCII string, assigned by a Member Agency Control Authority Office (MACAO) or the CCSDS, to distinguish among descriptions with the same Control Authority Identifier (CAID).

Label Value Object (LVO): The basic SFDU building block comprised of a LABEL field and a VALUE field. This structure is the fundamental structural element used to build SFDUs.

Member Agency Control Authority Office (MACAO): An individual CCSDS Participating Agency organization that has accepted the operational responsibilities and constraints specified within CCSDS Recommendations on Control Authority (CA) operations.

Open System Data Interchange: The process of transferring data from one open system to another. An open system is one which uses publicly available formats and protocols, so that anyone can communicate with the open system by following the open system standards. It should be noted that open system does not imply an uncontrolled or unrestricted access to the data.

Standard Formatted Data Unit (SFDU): Data that conform to CCSDS SFDU Recommendations for structure, construction rules, and field specification definition.

1.5.2 NOMENCLATURE

The following conventions apply throughout this Recommendation:

• a) the words 'shall' and 'must' imply a binding and verifiable specification;
• b) the word 'should' implies an optional, but desirable, specification;
• c) the word 'may' implies an optional specification;
• d) the words 'is', 'are', and 'will' imply statements of fact.

1.5.3 CONVENTIONS

This document uses syntax diagrams to illustrate the syntax of the Reference Environment Name Specifications. The following conventions are used.

• a) The item on the left of the:= symbol is being defined.
• b) The diagram on the right of the:= symbol is the definition.
• c) A vertical branch represents a choice.
• d) A repetition is indicated by a loop backwards covering the object(s) that may be repeated.

1.6 NORMATIVE REFERENCES

The following documents contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All documents are subject to revision, and users of this Recommendation 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 Recommendations.

ANNEX B

INFORMATIVE REFERENCES
(This annex is not part of the Recommendation.)

Purpose:

This annex provides a list of references which may be valuable to the user of this Recommendation as background material or to provide implementation guidelines for using this Recommendation.