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**RECOMMENDATION FOR SPACE**

**DATA SYSTEM STANDARDS**

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| **DATA ENTITY DICTIONARY SPECIFICATION LANGUAGE (DEDSL)---**          |
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| **ABSTRACT SYNTAX**                                                   |
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| **(CCSD0011)**                                                        |
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**CCSDS 647.1-B-1**

**BLUE BOOK**

June 2001

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AUTHORITY

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

       Issue:               Blue Book, Issue 1                         

       Date:                June 2001                                  

       Location:            Oxfordshire, England                       

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

This document has been approved for publication by the Management
Council of the Consultative Committee for Space Data Systems (CCSDS) and
represents the consensus technical agreement of the participating CCSDS
Member Agencies. The procedure for review and authorization of CCSDS
Recommendations is detailed in \[C1\], and the record of Agency
participation in the authorization of this document can be obtained from
the CCSDS Secretariat at the address below.

This document is published and maintained by:

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

STATEMENT OF INTENT

The Consultative Committee for Space Data Systems (CCSDS) is an
organisation officially established by the management of member space
Agencies. The Committee meets periodically to address data systems
problems that are common to all participants, and to formulate sound
technical solutions to these problems. Inasmuch as participation in the
CCSDS is completely voluntary, the results of Committee actions are
termed **Recommendations** and are not considered binding on any Agency.

This **Recommendation** is issued by, and represents the consensus of,
the CCSDS Plenary body. Agency endorsement of this **Recommendation** is
entirely voluntary. Endorsement, however, indicates the following
understandings:

o Whenever an Agency establishes a CCSDS-related **standard**, this
**standard** will be in accord with the relevant **Recommendation**.
Establishing such a **standard** does not preclude other provisions
which an Agency may develop.

o Whenever an Agency establishes a CCSDS-related **standard**, the
Agency will provide other CCSDS member Agencies with the following
information:

> -- The **standard** itself.
>
> -- The anticipated date of initial operational capability.
>
> -- The anticipated duration of operational service.

o Specific service arrangements shall be made via memoranda of
agreement. Neither this **Recommendation** nor any ensuing **standard**
is a substitute for a memorandum of agreement.

No later than five years from its date of issuance, this
**Recommendation** will be reviewed by the CCSDS to determine whether it
should: (1) remain in effect without change; (2) be changed to reflect
the impact of new technologies, new requirements, or new directions; or,
(3) be retired or canceled.

In those instances when a new version of a **Recommendation** is issued,
existing CCSDS-related Agency standards and implementations are not
negated or deemed to be non--CCSDS compatible. It is the responsibility
of each Agency to determine when such standards or implementations are
to be modified. Each Agency is, however, strongly encouraged to direct
planning for its new standards and implementations towards the later
version of the Recommendation.

FOREWORD

This Recommendation is a technical Recommendation that provides a model
and language to increase the standardisation of the expression of
semantic concepts that are to be carried with data. These semantic
concepts are given standard names, and a standard way of expressing them
is also provided. The semantic information may be conveyed either in a
computer-processable manner or via conventional (e.g., paper)
documentation.

Through the process of normal evolution, it is expected that expansion,
deletion or modification to this document may occur. This Recommendation
is therefore subject to CCSDS document management and change control
procedures defined in reference \[C1\]. 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.
>
> -- Central Research Institute of Machine Building (TsNIIMash)/Russian
> Federation.
>
> -- 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 HQ)/USA.
>
> -- National Space Development Agency of Japan (NASDA)/Japan.

[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 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.

-   Industry Canada/Communications Research Centre (CRC)/Canada.

-   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 and Issue**    **Date**     **Status**

  CCSDS          Data Entity Dictionary June 2001    Original Issue
  647.1-B-1.     Specification Language              
                 (DEDSL)---Abstract                  
                 Syntax                              
  -------------- ---------------------- ------------ ----------------------

CONTENTS

Section Page

1 INTRODUCTION
[1-1](#number-range-figurenumber-range-tablenumber-range-exampleintroduction)

1.1 PURPOSE AND SCOPE [1-1](#purpose-and-scope)

1.2 Applicability [1-2](#applicability)

1.3 Rationale [1-2](#rationale)

1.4 Document StructurE [1-3](#document-structure)

1.5 Definitions [1-4](#definitions)

1.6 References [1-7](#references)

2 OVERVIEW
[2-1](#number-range-examplenumber-range-figurenumber-range-tableoverview)

2.1 General [2-1](#general)

2.2 Uses of Data Entity Dictionaries
[2-1](#uses-of-data-entity-dictionaries)

2.3 Application of the DEDSL [2-6](#application-of-the-dedsl)

2.4 REGISTERING DED [2-8](#registering-ded)

3 DESCRIPTORS OF A DATA ENTITY ATTRIBUTE
[3-1](#number-range-examplenumber-range-figurenumber-range-tabledescriptors-of-a-data-entity-attribute)

3.1 General [3-1](#general-2)

3.2 List of descriptors [3-1](#list-of-descriptors)

3.3 ATTRIBUTE_NAME [3-3](#attribute_name)

3.4 ATTRIBUTE_DEFINITION [3-4](#attribute_definition)

3.5 ATTRIBUTE_OBLIGATION [3-5](#attribute_obligation)

3.6 ATTRIBUTE_CONDITION [3-6](#attribute_condition)

3.7 ATTRIBUTE_MAXIMUM_OCCURRENCE [3-6](#attribute_maximum_occurrence)

3.8 ATTRIBUTE_VALUE_TYPE [3-7](#attribute_value_type)

3.9 ATTRIBUTE_MAXIMUM_SIZE [3-9](#attribute_maximum_size)

3.10 ATTRIBUTE_ENUMERATION_VALUES [3-10](#attribute_enumeration_values)

3.11 ATTRIBUTE_COMMENT [3-10](#attribute_comment)

3.12 ATTRIBUTE_INHERITANCE [3-11](#attribute_inheritance)

3.13 ATTRIBUTE_DEFAULT_VALUE [3-11](#attribute_default_value)

3.14 ATTRIBUTE_VALUE_EXAMPLE [3-12](#attribute_value_example)

3.15 ATTRIBUTE_SCOPE [3-12](#attribute_scope)

4 DATA ENTITY ATTRIBUTES AND DATA ENTITY DICTIONARY ATTRIBUTES
[4-1](#number-range-examplenumber-range-figurenumber-range-tabledata-entity-attributes-and-data-entity-dictionary-attributes)

4.1 CONCEPT DEFINITIONS [4-1](#concept-definitions)

4.2 GENERAL VIEW OF THE STANDARD ATTRIBUTES
[4-2](#general-view-of-the-standard-attributes)

4.3 standard ATTRIBUTES for data entity dictionaries
[4-4](#standard-attributes-for-data-entity-dictionaries-1)

4.4 STANDARD ATTRIBUTES FOR DATA ENTITIES
[4-13](#standard-attributes-for-data-entities-1)

4.5 USER-DEFINED ATTRIBUTES [4-34](#user-defined-attributes)

4.6 RELATIONSHIP RULES [4-37](#relationship-rules)

5 IMPLEMENTATION GUIDELINES
[5-1](#number-range-examplenumber-range-figurenumber-range-tableimplementation-guidelines)

6 DEDSL CONFORMANCE: ABSTRACT DEDSL (ADID = CCSD0011)
[6-1](#number-range-examplenumber-range-figurenumber-range-tablededsl-conformance-abstract-dedsl-adid-ccsd0011)

6.1 General [6-1](#general-6)

6.2 CONFORMANCE LEVEL 1: BASE COMPLIANCE
[6-1](#conformance-level-1-base-compliance)

6.3 CONFORMANCE LEVEL 2: FULL COMPLIANCE
[6-1](#conformance-level-2-full-compliance)

ANNEX A DEDSL EXAMPLES
[A-1](#number-range-examplenumber-range-figurenumber-range-tablenumber-range-annex_level_1-dedsl-examples)

ANNEX B MAPPING OF THE CONCEPTS BETWEEN THIS RECOM-MENDATION AND THE
ISO/IEC 11179-3:1994 STANDARD
[B-1](#number-range-examplenumber-range-figurenumber-range-tablenumber-range-annex_level_1-mapping-of-the-concepts-between-this-recommendation-and-the-isoiec-11179-31994-standard)

ANNEX C INFORMATIVE REFERENCES
[C-1](#number-range-examplenumber-range-figurenumber-range-tablenumber-range-annex_level_1-informative-references)

Figure

2-1 Organisation of the Data Product Product_X
[2-2](#__RefHeading___Toc517077249)

2-2 Organisation of the Data Product Product_Y
[2-3](#__RefHeading___Toc517077250)

2-3 Organisation of the DED Relative to Product_X and Product_Y
[2-4](#__RefHeading___Toc517077251)

2-4 "Uses some models of" Links between Data Product Dictionaries
[2-6](#__RefHeading___Toc517077252)

Table

2-1 Comparison of Community DED and Product DED Descriptions
[2-5](#__RefHeading___Toc492883756)

3-1 General Descriptors [3-2](#__RefHeading___Toc492883757)

4-1 Data Entity Dictionary Attributes
[4-2](#__RefHeading___Toc492883758)

4-2 Data Entity Attributes [4-3](#__RefHeading___Toc492883759)

Example

3-1 Elementary Type [3-7](#__RefHeading___Toc493389414)

3-2 Ordered List of Elementary Types [3-8](#__RefHeading___Toc493389415)

3-3 Ordered List of the Same Elementary Type
[3-8](#__RefHeading___Toc493389416)

3-4 Use of Entity_Type [3-8](#__RefHeading___Toc493389417)

3-5 Use of Choice [3-8](#__RefHeading___Toc493389418)

CONTENTS (continued)

Example Page

3-6 Use of Attribute_Maximum_Size [3-9](#__RefHeading___Toc493389419)

3-7 Use of Attribute_Enumeration_Values
[3-10](#__RefHeading___Toc493389420)

4-1 Defining User-Defined Attribute [4-35](#__RefHeading___Toc493389421)

4-2 Defining User-Defined Attribute with an External Reference
[4-35](#__RefHeading___Toc493389422)

4-3 Usage of a User-Defined Attribute
[4-36](#__RefHeading___Toc493389423)

# Number range FigureNumber range TableNumber range ExampleINTRODUCTION

## PURPOSE AND SCOPE

This document provides an extensible way of defining data entity
dictionaries.

A Data Entity is a concept that can, or does, take on one or more
values. Semantics of a data entity, such as a text definition of its
meaning, are defined by attributes. The purpose of this Recommendation
is to define a language for specifying a dictionary which describes
semantics for a collection of data entities---it does not define a
specific dictionary.

A dictionary is understood as a mechanism that is able to organise a set
of information in a consistent and easily understandable manner, and it
is commonly used by humans to look up the meaning of words used in
natural languages. Similarly, a Data Entity Dictionary (DED) is used by
humans and systems to look up the definition, and other attributes, of
data entities used in the definition and generation of data products.

This document defines the abstract definition of the semantic
information that is required to be conveyed and presents the
specification in a layered manner (attributes, entities, dictionaries).
This is done so that the actual technique used to convey the information
is independent of the information content and, therefore, the same
abstract standard can be used within different formatting environments.
This also permits the semantic information to be translated to different
representations as may be needed when data are transferred across
different domains.

This Recommendation defines the concepts of name, definition, units, and
a small set of other standard attributes so that they may be used
consistently in the formation of data entity dictionaries. Given the
wide variety of data entities that may need to be described, only a few
of the attributes are made mandatory by this Recommendation.

The method used to define standard attributes can also be used to extend
the set of attributes beyond the standard ones provided within this
Recommendation.

Several classes of data entities are defined. These classes allow making
a distinction between the abstract data entities---the models---and the
concrete data entities---the data fields in a data product.

This Recommendation is strongly based on the International Organization
for Standardization (ISO)/International Electrotechnical Commission
(IEC) Specification and standardisation of data elements (reference
\[C11\]) with which it is widely consistent for all semantic aspects.
**However this Recommendation does not require knowledge of reference
\[C-11\] in order to be understood**.

## Applicability

This Recommendation is intended to be used by implementers of a concrete
syntax for Data Entity Dictionaries. Such dictionaries could then be
used for example:

-   by data producers to construct dictionaries that describe, in a more
    formal manner, data entities within their data products;

-   by data users to understand data received from data producers who
    have used this Recommendation to construct their dictionaries;

-   by an organisation that mandates the attributes used to define each
    entity description in dictionaries used within that organisation;

-   by a particular community, such as Earth observation, space physics,
    archives, etc., to establish a degree of standardisation for the
    contents of any data entity dictionary associated or not with a data
    product (this would be done by using this Recommendation to define a
    community-wide data entity dictionary);

-   by organisations and communities to exchange the contents of a data
    entity dictionary in a standardised manner, i.e., to facilitate
    interoperability.

## Rationale

A given data entity may take on a range of values that are represented
differently within different formats, including such generic formats
Hierarchical Data Format (HDF) (reference \[C-6\]), Common Data Format
(CDF) (reference \[C-7\]), or in native formats. However there is
information about that data entity, such as its definition and other
semantic attributes, which is independent of the values and their
representation in any given format.

Part of this information can be expressed in a data entity dictionary,
and this dictionary can be expressed in many different ways. For
example, it may be expressed in natural language paragraphs within a
document that accompanies a data product. It may be partially expressed
by attributes defined within generic or native data product formats,
while the rest may be in other documents. The concepts used in the
description of the data entities may vary widely, or subtly. These
concepts may not be documented at all.

Therefore, individuals and organisations that need to receive and
understand a variety of data products may waste considerable effort in
attempting to understand the data entities comprised by each data
product. This also greatly hinders the use of generic tools that can
assist in the recognition and presentation of this information in a way
that various individuals and organisations find most understandable.

To begin to address these issues across broad organisation and community
disciplines, it is first necessary to define a set of standard concepts
that can be used in the formation of data entity dictionaries within
those disciplines, and in the mapping of different dictionary concepts
between disciplines. To facilitate the creation of generic tools, it is
also necessary to define a standard representation for the standard
concepts. This Recommendation defines a small number of concepts, in
terms of attribute descriptors and standard attributes, which are
intended to be broadly applicable.

Finally, this Recommendation provides additional standardised
functionalities allowing the expression of relationships between
entities in a dictionary, as well as definitions of inter-relationships
between dictionaries.

## Document StructurE

The document is structured as follows:

-   Section 2 provides an overview of the data entity dictionary concept
    and describes through examples how this Recommendation may be used.
    It also provides a context enabling a better understanding of the
    standard specified in sections 3 and 4.

-   Section 3 specifies the standard descriptors which shall be used to
    define the attributes of data entities as well as of data entity
    dictionaries.

-   Section 4 specifies the standard attributes to be used to define
    data entities and data entity dictionaries. It also presents the
    method to define user-defined attributes and the implementation
    guidelines.

-   Section 5 discusses implementation guidelines.

-   Section 6 discusses levels of conformance with this Recommendation.

-   Annex A provides examples implementing the concepts described in
    sections 3 and 4.

-   Annex B provides the mapping of the concepts between this
    Recommendation and the ISO/IEC 11179-3:1994 standard (reference
    \[C-11\]).

-   Annex C provides a list of references that may be valuable to the
    user of this Recommendation as background material or as
    implementation guidelines for using this Recommendation.

## Definitions

### ACRONYMS and abbreviations

This subsection defines the acronyms and abbreviations used throughout
this Recommendation:

  ------------- ---------------------------------------------------------
  ADID          Authority and Description Identifier

  ASCII         American Standard Code for Information Interchange

  CCSDS         Consultative Committee for Space Data Systems

  CDF           Common Data Format

  DDL           Data Definition Language

  DED           Data Entity Dictionary

  DEDSL         Data Entity Dictionary Specification Language

  EAST          Enhanced Ada SubseT

  FITS          Flexible Image Transport System

  HDF           Hierarchical Data Format

  ID            Identifier

  ISO           International Organization for Standardization

  LVO           Label Value Object

  MACAO         Member Agency Control Authority Office

  PVL           Parameter Value Language

  SFDU          Standard Formatted Data Unit

  XML           eXtended Mark-up Language
  ------------- ---------------------------------------------------------

### Glossary of Terms

For the purpose of this document, the following definitions apply:

  --------------------- ---------------------------------------------------------
  **Attribute**         A piece of information that describes a Data Entity or
                        Dictionary Entity. This information characterizes or
                        enhances the understanding of the data that is described.
                        Attributes are used to define the semantics of data
                        entities.

  **Attribute           A piece of information that describes an attribute. This
  Descriptor**          document specifies a set of descriptors for attribute
                        description.

  **Attribute Value**   A value associated with an attribute instance.

  **Composite Data      A data entity which consists of a combination of various
  Entity**              other elementary and composite entities.

  **Constant**          A named constant value that is used within a dictionary
                        but is not part of the data themselves. Use of constants
                        enables data entity dictionaries to specify values which
                        will be used by several projects or within a domain
                        (astronomy constants, image size, etc).

  **Data Entity**       A concept that can, or does, take on one or more values.
                        The concept, and optionally constraints on the
                        representation of its value, are defined by attributes
                        and their values.

  **Data Entity         A collection of semantic definitions of various data
  Dictionary**          entities, together with a few mandatory and optional
                        attributes about the collection as a whole. Data entity
                        dictionaries may be just for a single product, i.e., all
                        the data entities within a single product are described
                        in a corresponding single dictionary, or the data entity
                        dictionary may be a discipline-oriented dictionary that
                        holds a number of previously defined data entity
                        definitions which may be used by data designers and users
                        as references. Some parts of a dictionary are optional.
                        In practical terms the dictionary could be a file or a
                        Standard Formatted Data Unit (SFDU) Label-Value Object
                        (LVO) value field (references \[1\] and \[C-4\]). Within
                        this Recommendation, the expression 'data entity
                        dictionary' can refer either to the notion of data entity
                        dictionaries or to a data entity dictionary instance. A
                        data entity dictionary is also an entity, called
                        Dictionary Entity.

  **Data Product**      A collection of one or more data items that are packaged
                        for or by a specific application.

  **Defaulted**         Indication of an attribute or descriptor value that is
                        understood when the attribute or descriptor is not
                        explicitly included in the containing definition.

  **Descriptor Name**   An Identifier that is the name of the descriptor.

  **Descriptor Type**   The characterization of the descriptor value; e.g., text,
                        identifier, integer.

  **Elementary Data     A data entity whose data type is elementary, that is,
  Entity**              Integer, Real, Text or Enumerated.

  **Enumerated**        A set containing a restricted number of discrete values,
                        where each discrete value is named and unique within the
                        set.

  **Identifier**        A sequence of characters that designates something.

  **Inter-operability   Set of constraints enabling an easier exchange of
  Constraints**         dictionaries using different DEDSL implementations.

  **Model**             A data entity described independently from any instance
                        in a data product, and corresponding to a re-usable data
                        entity definition, from which other data entities may
                        inherit the attributes and apply some specialization
                        rules.

  **Semantics**         Information that defines the meaning rather than the
                        physical representation of data. Semantics potentially
                        cover a very large domain, from the simple domain, such
                        as the units of one data entity, to a more complex one,
                        such as the relationship between one data entity and
                        another.

  **Standard            One of the attributes defined within this Recommendation.
  Attribute**           

  **Syntax**            Information defining the physical representation of data.
                        It includes the structural arrangement of the fields
                        within the data on the exchanged media.

  **Text**              A delimited sequence of characters. The set of allowed
                        characters is defined in the Data Entity Dictionary.

  **User Defined        An attribute that is defined by a particular user or
  Attribute**           project and after definition is then used in the same
                        manner as a Standard Attribute within that data entity
                        dictionary.
  --------------------- ---------------------------------------------------------

### Nomenclature

The following conventions apply throughout this Recommendation:'

a)  the words 'shall' and 'must' imply 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.

### COnventions

[Convention 1:]{.underline}

No **Identifiers** or encoding values in the document are
case-sensitive.

[Convention 2:]{.underline}

The words which appear in bold characters throughout this Recommendation
correspond to the keywords or the major concepts of this Recommendation.

For example, when defining the descriptors, the descriptor name as well
as the descriptor type and sometimes the predefined values of the type
are in bold characters to enlighten the definition. This convention also
applies when defining the attributes (respectively attribute name and
attribute value type).

[Convention 3:]{.underline}

Text values are delimited by quotes in the examples for clarity.

[Convention 4:]{.underline}

Parentheses are used to delimit ordered lists, with commas used to
separate the elements of the list.

[Convention 5:]{.underline}

Interoperability constraints are a set of constraints enabling an easier
exchange of dictionaries using different DEDSL implementations and may
appear within the description of the descriptors and attributes
specified by this Recommendation. For example, they may refer to the
size of the value of an attribute or the coding values of a descriptor.
Interoperability constraints determine the two levels of conformance
identified in section 6. Interoperability constraints are introduced by
the title '***Interoperability Constraints***'.

## References

The following documents contain provisions (through references within
this text) which constitute provisions of this Recommendation. At the
time of the publication the indicated editions 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 available CCSDS Recommendations.

\[1\] *Standard Formatted Data Units---Structure and Construction
Rules*. Recommendation for Space Data System Standards, CCSDS 620.0-B-2.
Blue Book. Issue 2. Washington, D.C.: CCSDS, May 1992. (ISO 12175)

\[2\] *ASCII Encoded English (CCSD0002)*. Recommendation for Space Data
System Standards, CCSDS 643.0-B-1. Blue Book. Issue 1. Washington, D.C.:
CCSDS, November 1992. (ISO 14962)

\[3\] *Information Processing---Representation of numerical values in
character strings for information interchange*. ISO 6093-1985. Geneva:
ISO, 1985.

\[4\] *Standard Formatted Data Units---Control Authority Procedures.*
Recommendation for Space Data System Standards, CCSDS 630.0-B-1. Blue
Book. Issue 1. Washington, D.C.: CCSDS, June 1993. (ISO 13764)

\[5\] *Codes for the Representation of Names of Languages*. ISO 639-2
-1998. Geneva: ISO, 1998.

\[6\] *Information Processing---8-Bit Single-Byte Coded Graphic
Character Sets---Part 1: Latin Alphabet No. 1*. International Standard,
ISO 8859-1:1987. Geneva: ISO, 1987.

\[7\] *Information Processing---Representation of SI and Other Units in
Systems with Limited Character Sets.* International Standard, ISO
2955-1983. Geneva: ISO, 1983.

# Number range ExampleNumber range FigureNumber range TableOVERVIEW

## General

As discussed in subsection 1.1, a Data Entity Dictionary is used by
humans and systems to look up the definition and other attributes of
data entities. This section discusses some of the primary uses of data
entity dictionaries and presents a basic example of DEDSL usage.

Other detailed examples are given in annex A.

## Uses of Data Entity Dictionaries

### product data entity dictionaries

So that its contained data can be extracted, a data product can appear
with a formatting standard (e.g., Flexible Image Transport System
\[FITS\]), or a self-describing format (e.g., CDF, HDF, etc.) or a Data
Definition Language (e.g., EAST). This syntactic information may not be
easy to understand and a formal definition of additional semantics may
be necessary, which leads to the definition of a product Data Entity
Dictionary.

Figure 2-1 shows the structure of the data product (**PRODUCT_X**). It
is made up of a header (**HEADER**) and an image (**DATA_1**). The
header contains a product identifier (**PRODUCT_ID**), information about
the station, which has acquired the data, (**ACQ_STATION**), information
about the acquisition time (**ACQ_TIME**), and information necessary for
the processing of the image, e.g., the centre coordinates
\[**CENTRE_COORD** (**LATITUDE** and **LONGITUDE**)\]. Its physical
description, possibly expressed using a DDL, may not be readily
understandable to all readers because it includes a specification to the
bit level. It is also useful to have a quick overview of the product and
to have additional semantic information. Therefore, the definition of a
product data entity dictionary (**PRODUCT_X DED**) will bring this
necessary information and perspective.

Within this data entity dictionary additional information can be given
to more precisely define:

-   the definition of each data entity;

-   the kinds of values used for the centre coordinates **LATITUDE** and
    **LONGITUDE.**

The values of **LATITUDE** are defined relative to the Equator and range
from -90.000 to +90.000, while the values of **LONGITUDE** are defined
to be relative to Greenwich and range from -180.00 to +180.00. The units
used to express the values are to be in degrees. All this information
may be included in the data entity dictionary.

These pieces of semantic information correspond to the existing data
entities of the product.

Consequently, the **PRODUCT_X DED** will contain the semantic
descriptions of the following data entities:

-   HEADER;

-   PRODUCT_ID;

-   ACQ_STATION;

-   ACQ_TIME;

-   CENTRE_COORD;

-   LATITUDE;

-   LONGITUDE;

-   DATA_1.

![](media/image3.wmf){width="5.0in" height="2.6in"}

Figure 2-1: Organisation of the Data Product
Product_X[]{#__RefHeading___Toc517077249 .anchor}1

Figure 2-2 shows the structure of another data product (**PRODUCT_Y**).
It is made up of the product identifier (**PRODUCT_ID**), the centre
coordinates (e.g., a latitude, a longitude) and the acquired image
(**DATA_2**). A data product dictionary (**PRODUCT_Y DED**) can also be
defined for **PRODUCT_Y** in the same way as for **PRODUCT_X**.

Consequently, the **PRODUCT_Y DED** will contain the semantic
descriptions of the following data entities:

-   PRODUCT_ID;

-   LATITUDE;

-   LONGITUDE;

-   DATA_2.

![](media/image4.wmf){width="5.0in" height="2.591666666666667in"}

Figure 2-2: Organisation of the Data Product
Product_Y[]{#__RefHeading___Toc517077250 .anchor}2

Looking at the two previously described data products it seems
convenient to define **PRODUCT_Y DED** by re-using some data entity
descriptions of **PRODUCT_X DED.**

The data entity descriptions which seem common to both data products are
**PRODUCT_ID, LATITUDE** and **LONGITUDE**.

Therefore the data product dictionary **PRODUCT_X** can be modified so
that those data entity descriptions become re-usable **models**. These
models are abstract data descriptions to which concrete descriptions,
i.e., corresponding to data entities within the data product, can refer.
Then the DED associated with **PRODUCT_Y** can refer to the DED
associated with **PRODUCT_X** for the definition of some of its semantic
descriptions using the models of the **PRODUCT_X DED.**

Consequently, the **PRODUCT_X DED** will contain data entity
descriptions corresponding to abstract definitions (models) and named as
follows:

-   PRODUCT_ID_MODEL;

-   LATITUDE_MODEL;

-   LONGITUDE_MODEL.

The **PRODUCT_X DED** will still contain the semantic descriptions
corresponding to the following data entities, but with references to the
newly defined models:

-   HEADER;

-   PRODUCT_ID, inheriting from the model PRODUCT_ID_MODEL;

-   ACQ_STATION;

-   ACQ_TIME;

-   CENTRE_COORD;

-   LATITUDE, inheriting from the model LATITUDE_MODEL;

-   LONGITUDE, inheriting from the model LONGITUDE_MODEL;

-   DATA_1.

The **PRODUCT_Y DED** will still contain the semantic descriptions
corresponding to the following data entities, but with references to the
newly defined models:

-   PRODUCT_ID, inheriting from the model PRODUCT_ID_MODEL;

-   LATITUDE, inheriting from the model LATITUDE_MODEL;

-   LONGITUDE, inheriting from the model LONGITUDE_MODEL;

-   DATA_2.

    Figure 2-3 presents the resulting organisation between both DEDs as
    they are used to support PRODUCT_Y.

![](media/image5.wmf){width="5.0in" height="2.591666666666667in"}

Figure 2-3: Organisation of the DED Relative to Product_X and
Product_Y[]{#__RefHeading___Toc517077251 .anchor}3

### community data entity dictionaries

The project or the data designer may consider that a community
dictionary is necessary because there are several data products related
to the same kind of data.

Looking at the two products given as examples, they may decide that the
community data entity dictionary should include the following entities
which frequently appear: **PRODUCT_ID**, **ACQ_STATION**,
**ACQ_TIME**,**LATITUDE** and **LONGITUDE**.

This community DED will contain a normalized description of these
entities which can then be considered as **models**. Data entities being
latitudes and longitudes and appearing within other data products will
then have the same associated semantic information whenever they inherit
from these normalized descriptions.

The other data entities only appearing in a data product such as
**DATA_1**, **DATA_2** and **CENTRE_COORD** are local definitions.

The purpose of a community dictionary is to provide, across different
data products, a standard or normalized definition of data entities.

Table 2-1 shows an example of mapping of the community DED entries into
data product DED entries for the data products shown in figures 2-1 and
2-2, according to the choices made by the project or data designers.

Table 2-1: Comparison of Community DED and Product DED
Descriptions[]{#__RefHeading___Toc492883756 .anchor}1

  ---------------- --------------- ----------- ------------- -------------
  **Concept**      **Data Type**   **Found in  **Found in    **Found in
                                   Community   PRODUCT_X**   PRODUCT_Y**
                                   DED**       **DED**       **DED**

  HEADER           Composite       no          yes           no

  PRODUCT_ID       Text            yes         yes           yes

  ACQ_STATION      Enumeration     yes         yes           no

  ACQ_TIME         Composite       yes         yes           no

  CENTRE_COORD     Composite       no          yes           no

  LATITUDE         Real            yes         yes           yes

  LONGITUDE        Real            yes         yes           yes

  DATA 1           Composite       no          yes           no
                   (Array of                                 
                   16-bit                                    
                   integers)                                 

  DATA 2           Composite       no          no            yes
                   (Array of real                            
                   numbers)                                  
  ---------------- --------------- ----------- ------------- -------------

Supposing that the project has defined its community dictionary, when it
defines a new data product or for example when it rewrites the
dictionary related to **PRODUCT_X** (in figure 2-1), it can decide to
define the **HEADER** entity on the basis of **PRODUCT_ID**,
**ACQ_STATION** and **ACQ_TIME**, which inherit from the corresponding
data entities in the community dictionary, i.e., which then have the
same properties as the model data entities. The project can also decide
to define the **CENTRE_COORD** entity on the basis of the **LATITUDE**
and **LONGITUDE** entities, which inherit from the corresponding data
entities in the community dictionary. The **DATA1** entity does not
inherit from a specific data entity described in the community DED, as
it appears to be a kind of data only appearing in the data product
**PRODUCT_X**.

The same policy can be applied to **PRODUCT_Y** of figure 2-2.

Therefore we can consider the links 'uses some models of', in figure
2-4, among the three data entity dictionaries. A 'uses some models of'
link between **PRODUCT_X DED** and the domain DED means that some data
entities of **PRODUCT_X** inherit from corresponding data entities
contained in the domain DED.

![](media/image6.wmf)

Figure 2-4: 'Uses some models of' Links between Data Product
Dictionaries[]{#__RefHeading___Toc517077252 .anchor}4

## Application of the DEDSL

### General

As demonstrated in the previous section, there are two major uses for
dictionaries:

-   to describe a data product semantically;

-   to build up and define a community DED.

This Recommendation focuses on developing standard names and
descriptions for the concepts required for Data Entity Dictionaries, and
formally defines the concepts of name, definition, units, and a small
set of other attributes so they may be used consistently in the
formation of data entity dictionaries. A method is also provided to
permit the set of attributes to be extended beyond the standard ones
provided within this Recommendation.

This formal definition enables the definition of generic tools to assist
producers in creating documented products, and to assist consumers in
understanding the products they receive.

### PRODUCT data entity dictionaries

A product DED is a means for an organisation to present the semantics
necessary for a good understanding of a managed data product. A product
DED is dependent of the data product description. However, an enhanced
understanding is only possible when the semantics associated with the
products are presented in a common, i.e., standardised way.

Therefore, this Recommendation provides a foundation for the creation of
a product DED by providing a basic set of concepts for data entity
descriptions. This Recommendation also provides the formal methods to
describe relationships among the data entities of the product DEDs.

### community data entity dictionaries

A community DED is also a means for an organisation to gain some degree
of control/standardisation over the data descriptions created by member
data producers. Unlike product data entity dictionaries, these community
DED are not used in conjunction with a specific product description
technique. They are independent of the specific implementation of
products. Examples of uses of community DED include:

-   the creation of a standard data entity dictionary by an organisation
    that mandates the attributes defining each entity description in
    dictionaries used within that organisation;

-   the creation of a community DED by a particular community (e.g.,
    planetary science, astrophysics, etc.), to establish a degree of
    standardisation for the contents of any data entity dictionary
    associated with a data product from that community.

This Recommendation provides a foundation for the creation of community
DED and also provides the formal methods to describe relationships among
data entities of multiple data entity dictionaries.

## REGISTERING DED

Whenever a project or data designer has defined a product DED, it makes
sense to register it as it may apply to multiple instances of the
product and this makes it easier to find and retrieve for dissemination
or updating.

Whenever a project or data designer has defined a community DED, they
can decide to register it at different levels:

-   in the framework of any organisation dealing with data of a
    particular domain or project;

-   internally within an agency;

-   within the CCSDS community.

For example, whenever a member agency considers that one of its
particular community DED corresponds to the needs of other agencies, it
may submit its DEDs to an organisation conforming to the CCSDS
(references \[4\] and \[C5\]) or ISO registration procedures.

# Number range ExampleNumber range FigureNumber range TableDESCRIPTORS OF A DATA ENTITY ATTRIBUTE

## General

### The semantic information required for describing a data entity is seen as a collection of attributes. Each attribute describes a particular semantic characteristic of the data entity. {#the-semantic-information-required-for-describing-a-data-entity-is-seen-as-a-collection-of-attributes.-each-attribute-describes-a-particular-semantic-characteristic-of-the-data-entity. .Paragraph-3}

### Data entity attributes shall be registered and controlled in a standard way in order to achieve consistency in the exchange of information on data entities among data entity dictionaries, and to enable the comparison of data entities used in different management environments. {#data-entity-attributes-shall-be-registered-and-controlled-in-a-standard-way-in-order-to-achieve-consistency-in-the-exchange-of-information-on-data-entities-among-data-entity-dictionaries-and-to-enable-the-comparison-of-data-entities-used-in-different-management-environments. .Paragraph-3}

### Therefore, this Recommendation defines a list of general descriptors for describing a data entity attribute. {#therefore-this-recommendation-defines-a-list-of-general-descriptors-for-describing-a-data-entity-attribute. .Paragraph-3}

## List of descriptors

### A data entity attribute is specified by means of attribute descriptors. {#a-data-entity-attribute-is-specified-by-means-of-attribute-descriptors. .Paragraph-3}

### A descriptor is either mandatory, conditional, optional or defaulted when a data entity attribute is defined: {#a-descriptor-is-either-mandatory-conditional-optional-or-defaulted-when-a-data-entity-attribute-is-defined .Paragraph-3}

-   **mandatory**: always required;

-   **conditional**: required under specified conditions;

-   **optional**: allowed but not required;

-   **defaulted**: provides a default value for the descriptor when the
    descriptor is omitted.

### A descriptor can only appear once in a data entity attribute description and the descriptor name is not case-sensitive. {#a-descriptor-can-only-appear-once-in-a-data-entity-attribute-description-and-the-descriptor-name-is-not-case-sensitive. .Paragraph-3}

NOTE -- Table 3-1 provides the set of general descriptors defined by
this Recommendation. The obligation column indicates whether a
descriptor is mandatory (M), conditional (C), optional (O) or defaulted
(D).

Table 3-1: General Descriptors[]{#__RefHeading___Toc492883757 .anchor}1

  -------------------------------------------------------- --------------
  descriptor of attribute                                  obligation

  ATTRIBUTE_NAME                                           M

  ATTRIBUTE_DEFINITION                                     M

  ATTRIBUTE_OBLIGATION                                     M

  ATTRIBUTE_CONDITION                                      C

  ATTRIBUTE_MAXIMUM_OCCURRENCE                             M

  ATTRIBUTE_VALUE_TYPE                                     M

  ATTRIBUTE_MAXIMUM_SIZE                                   O

  ATTRIBUTE_ENUMERATION_VALUES                             C

  ATTRIBUTE_COMMENT                                        O

  ATTRIBUTE_INHERITANCE                                    D

  ATTRIBUTE_DEFAULT_VALUE                                  C

  ATTRIBUTE_VALUE_EXAMPLE                                  O

  ATTRIBUTE_SCOPE                                          D
  -------------------------------------------------------- --------------

## ATTRIBUTE_NAME

+---------------+------------------------------------------------------+
| ***Purpose*** | Label assigned to a data entity attribute.           |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_name**.                                  |
+---------------+------------------------------------------------------+
| ***           | This descriptor is mandatory.                        |
| Obligation*** |                                                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is of type              |
| Type***       | **Identifier.**                                      |
|               |                                                      |
|               | The **attribute_name** shall be unique within a Data |
|               | Entity Dictionary.                                   |
+---------------+------------------------------------------------------+
|               |                                                      |
+---------------+------------------------------------------------------+
| ***Int        | The maximum length for the value of this descriptor  |
| eroperability | is 40 characters. The Identifier is not              |
| Constraint*** | case-sensitive.                                      |
|               |                                                      |
|               | The Identifier shall not contain any white spaces    |
|               | (e.g., one or more space characters, carriage        |
|               | returns, line feeds, form feeds or tabs).            |
|               |                                                      |
|               | It shall begin with a letter and may be followed by  |
|               | letters, digits or the underline character.          |
|               |                                                      |
|               | It shall end with a letter or a digit.               |
|               |                                                      |
|               | It shall only contain characters in a visibly        |
|               | displayable form.                                    |
+---------------+------------------------------------------------------+

## ATTRIBUTE_DEFINITION

+---------------+------------------------------------------------------+
| ***Purpose*** | The definition is required to give the description   |
|               | of the data entity attribute. This definition is     |
|               | intended for human readership and therefore any      |
|               | information that increases the understanding of the  |
|               | identified attribute should be included.             |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_definition**.                            |
+---------------+------------------------------------------------------+
| ***           | This descriptor is mandatory.                        |
| Obligation*** |                                                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is of type **Text**.    |
| Type***       |                                                      |
+---------------+------------------------------------------------------+
|               |                                                      |
+---------------+------------------------------------------------------+
| ***Int        | It is intended that the value of this descriptor can |
| eroperability | be of a significant length and hence provide a       |
| Constraint*** | description of the attribute as complete as          |
|               | possible.                                            |
|               |                                                      |
|               | The maximum length for the value of this descriptor  |
|               | is 8000 characters.                                  |
+---------------+------------------------------------------------------+

## ATTRIBUTE_OBLIGATION

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor indicating whether a data entity          |
|               | attribute shall always be present, or only sometimes |
|               | present, according to specified conditions.          |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_obligation**.                            |
+---------------+------------------------------------------------------+
| ***           | This descriptor is mandatory.                        |
| Obligation*** |                                                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is of type              |
| Type***       | **Enumerated** with values corresponding to the      |
|               | following cases:                                     |
|               |                                                      |
|               | -   **mandatory**: the data entity attribute shall   |
|               |     always be present.                               |
|               |                                                      |
|               | -   **conditional**: the data entity attribute shall |
|               |     be present if conditions specified by the        |
|               |     descriptor **attribute_condition** occur for the |
|               |     same data entity attribute.                      |
|               |                                                      |
|               | -   **optional**: the data entity attribute may be   |
|               |     present or not.                                  |
|               |                                                      |
|               | -   **defaulted**: a data entity attribute that      |
|               |     assumes a specified default value if it is       |
|               |     omitted from a data entity description. The      |
|               |     specified default value is provided by the       |
|               |     **attribute_default_value** descriptor.          |
|               |     Composite attributes, that is attributes whose   |
|               |     attribute_value_type is a List or Choice, shall  |
|               |     not have an obligation of defaulted.             |
+---------------+------------------------------------------------------+
|               |                                                      |
+---------------+------------------------------------------------------+
| ***Int        | The coding values are 'M' or 'mandatory', 'C' or     |
| eroperability | 'conditional', 'O' or 'optional' and 'D' or          |
| Constraint*** | 'defaulted'; these values are not case-sensitive.    |
+---------------+------------------------------------------------------+

## ATTRIBUTE_CONDITION

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor indicating the circumstances under which  |
|               | a data entity attribute shall be present.            |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_condition**.                             |
+---------------+------------------------------------------------------+
| ***           | This descriptor is conditional.                      |
| Obligation*** |                                                      |
|               | It shall be present if the **attribute_obligation**  |
|               | descriptor of the same data entity attribute has the |
|               | value '**conditional**'.                             |
+---------------+------------------------------------------------------+
| ***Descriptor | The value is of type **Text**.                       |
| Type***       |                                                      |
+---------------+------------------------------------------------------+
|               |                                                      |
+---------------+------------------------------------------------------+
| ***Int        | The maximum length for the value of this descriptor  |
| eroperability | is 8000 characters.                                  |
| Constraint*** |                                                      |
|               | It does not exclude the possibility of defining a    |
|               | particular formalism for the text itself, enabling   |
|               | the automatic processing of the text.                |
+---------------+------------------------------------------------------+

## ATTRIBUTE_MAXIMUM_OCCURRENCE

  --------------------- -------------------------------------------------------
  ***Purpose***         Descriptor specifying the maximum number of instances
                        which the data entity attribute may have in the
                        specification of a data entity.

  ***Descriptor Name*** The standard term to be used for this descriptor is
                        **attribute_maximum_occurrence**.

  ***Obligation***      This descriptor is mandatory.

  ***Descriptor Type*** The value of this descriptor is of type **Integer,** or
                        of type **Character** with the value of '**n**'. The
                        character 'n' specifies that there is no upper limit on
                        the number of times that the data entity attribute may
                        occur.

                        

  ***Interoperability   'n' denoting an unlimited number is not case-sensitive.
  Constraint***         
  --------------------- -------------------------------------------------------

## ATTRIBUTE_VALUE_TYPE

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor specifying a set of distinct values for   |
|               | representing the attribute value.                    |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_value_type**.                            |
+---------------+------------------------------------------------------+
| ***           | This descriptor is mandatory.                        |
| Obligation*** |                                                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor can be of type          |
| Type***       | Enumerated with the following values:                |
|               | **Enumerated**, **Integer**, **Real**, **Text**,     |
|               | **Identifier, Entity_Type**.                         |
|               |                                                      |
|               | When the value of the descriptor is **Entity_Type**  |
|               | then the attribute value must be an instance of the  |
|               | type of the data entity being defined; this type may |
|               | be Enumerated, Integer, Real, Text or Composite and  |
|               | cannot be an Identifier.                             |
|               |                                                      |
|               | The descriptor value can also be made up of an       |
|               | ordered list of elementary types or an included list |
|               | or choice. (Note that in the examples in this        |
|               | document we use parentheses with comma delimited     |
|               | elements to show the elements of the list, indicated |
|               | by the initial keyword **List**.). When the          |
|               | descriptor value is an ordered list of the same      |
|               | elementary type, it indicates that there may be an   |
|               | indefinite repetition of the same elementary type.   |
|               |                                                      |
|               | The descriptor value can be specified as a choice    |
|               | among a list of elementary types or an included list |
|               | or choice. (Note that in the examples in this        |
|               | document we use parentheses with comma delimited     |
|               | elements, to delimit elements in a choice, indicated |
|               | by the initial keyword **Choice**.)                  |
+---------------+------------------------------------------------------+

Note that the following examples show the use of attribute_value_type as
used in the definition of the standard attributes for data entities that
are defined in subsection 4.4.

NOTE -- The following example presents an attribute of elementary type:

For the definition of the attribute called **name** that identifies the
data entity, the attribute_value_type specifies that a value of this
attribute is an identifier.

**attribute_value_type: Identifier**

Example 3-1: Elementary Type[]{#__RefHeading___Toc493389414 .anchor}1

NOTE -- The following example presents an attribute type defined as a
set of two elementary types:

For the definition of the attribute called **alias** that defines an
alternative name of a data entity, the attribute_value_type specifies
that a value of this attribute is composed of the alternative name (of
the type **Text**) followed by the context in which this alias is used
(of the type **Text**).

**attribute_value_type: List(Text, Text)**

Example 3-2: Ordered List of Elementary
Types[]{#__RefHeading___Toc493389415 .anchor}2

NOTE -- The following example presents an attribute type defined as an
indefinite repetition of the same elementary type:

For the definition of the attribute called **enumeration_values** that
provides the set of permitted values of data entities of type
Enumerated, the attribute_value_type specifies that a value of this
attribute is an indefinite repetition of the same elementary type which
is **Identifier**.

**attribute_value_type: List(Identifier)**

Example 3-3: Ordered List of the Same Elementary
Type[]{#__RefHeading___Toc493389416 .anchor}3

NOTE -- The following example illustrates the use of Entity_Type:

For the definition of the attribute called **specific_instance** that
provides a specific value of the data entity occurrence, the
attribute_value_type specifies that a value of this attribute is
composed by a specific value (of the type **Entity_Type**) followed of
the meaning and context of this specific value (of the type **Text**).

**attribute_value_type: List(Entity_Type, Text)**

Example 3-4: Use of Entity_Type[]{#__RefHeading___Toc493389417 .anchor}4

NOTE -- The following example illustrates the use of Choice:

For the definition of the attribute called **text_size** that provides a
limitation on the size of the values of data entities of type Text, the
attribute_value_type specifies that a value of this attribute is either
the exact size of the text when known (of the type **Integer**) or a
list made up of the minimum and the maximum number of characters the
text may contain (both being of type **Integer**).

**attribute_value_type: Choice (Integer, List(Integer, Integer))**

Example 3-5: Use of Choice[]{#__RefHeading___Toc493389418 .anchor}5

## ATTRIBUTE_MAXIMUM_SIZE

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor specifying the maximum number of          |
|               | characters for representing the value of the         |
|               | attribute.                                           |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_maximum_size**.                          |
+---------------+------------------------------------------------------+
| ***           | This descriptor is optional.                         |
| Obligation*** |                                                      |
|               | It shall be present if the **attribute_value_type**  |
|               | value is **Identifier** or **Text**.                 |
|               |                                                      |
|               | It may be present for composite attributes made up   |
|               | of Identifiers or Texts. It then represents the size |
|               | allowed for each component of the set.               |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is of type **Integer**  |
| Type***       | when the **attribute_value_type** value is           |
|               | **Identifier** or **Text.**                          |
|               |                                                      |
|               | When the attribute is composite made up of           |
|               | Identifiers or Texts expressed as **List** or        |
|               | **Choice**, the value of this descriptor follows the |
|               | same formalism as the one defined for the descriptor |
|               | **attribute_value_type**.                            |
+---------------+------------------------------------------------------+

NOTE -- The following example illustrates the definition of the
attribute_maximum_size for a composite attribute.

For the definition of the attribute called **relation** that expresses a
relationship between two entity definitions and whose
**attribute_value_type** is expressed as
'**Choice(List(Text,Identifier), List(Text,Identifier,Identifier))**',
attribute_maximum_size specifies the size allowed for each component as
follows:

**attribute_maximum_size** **: Choice(List(8000, 400),
List(8000,400,400))**

Example 3-6: Use of
Attribute_Maximum_Size[]{#__RefHeading___Toc493389419 .anchor}6

## ATTRIBUTE_ENUMERATION_VALUES

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor specifying the distinct and discrete      |
|               | values of the attribute.                             |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_enumeration_values**.                    |
+---------------+------------------------------------------------------+
| ***           | This descriptor is conditional.                      |
| Obligation*** |                                                      |
|               | It shall be present if the **attribute_value_type**  |
|               | value is **Enumerated**.                             |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is a comma-separated    |
| Type***       | set of **Identifier** within parentheses without any |
|               | leading keyword.                                     |
+---------------+------------------------------------------------------+
| ***Int        | The interoperability constraints defined in 3.2      |
| eroperability | relative to Identifiers also apply here.             |
| Constraint*** |                                                      |
+---------------+------------------------------------------------------+

NOTE -- The following example illustrates the definition of the
descriptor:

For the definition of the attribute called **data_type** that provides
the type of the data entity occurrence, the attribute_enumeration_values
specifies the distinct allowed types.

**attribute_enumeration_values** **: (enumerated, text, real, integer,
composite)**

Example 3-7: Use of
Attribute_Enumeration_Values[]{#__RefHeading___Toc493389420 .anchor}7

## ATTRIBUTE_COMMENT

  --------------------- -------------------------------------------------------
  ***Purpose***         Descriptor providing information which is not directly
                        required to understand the meaning of the attribute,
                        but which could still assist the user of the attribute
                        in some manner. It may also contain examples.

  ***Descriptor Name*** The standard term to be used for this descriptor is
                        **attribute_comment**.

  ***Obligation***      This descriptor is optional.

  ***Descriptor Type*** The value of this descriptor is a of type **Text**.

  ***Interoperability   The maximum length for the value of this descriptor is
  Constraint***         8000 characters.
  --------------------- -------------------------------------------------------

## ATTRIBUTE_INHERITANCE

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor providing information about the           |
|               | inheritance rules for the attribute in a context of  |
|               | data entity modeling.                                |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_inheritance**.                           |
+---------------+------------------------------------------------------+
| ***           | This descriptor is defaulted.                        |
| Obligation*** |                                                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is of type              |
| Type***       | **Enumerated** with two discrete values:             |
|               | **inheritable** and **not_inheritable**.             |
|               |                                                      |
|               | The context is as follows: a data entity description |
|               | A inherits from another data entity description B.   |
|               | The following cases describe what may happen for the |
|               | values of the attributes of A for the different      |
|               | possible values of attribute_inheritance for the     |
|               | attributes of B.                                     |
|               |                                                      |
|               | -   When the value of an attribute of B cannot be    |
|               |     inherited, the attribute may be defined locally  |
|               |     in the description of A.                         |
|               |                                                      |
|               | -   When the value of an attribute of B can be       |
|               |     inherited, the value of this attribute is the    |
|               |     value of the corresponding attribute of A, to    |
|               |     which specialization rules have been applied as  |
|               |     defined in 4.6.3.                                |
+---------------+------------------------------------------------------+
| ***Default    | **inheritable**                                      |
| value***      |                                                      |
+---------------+------------------------------------------------------+

## ATTRIBUTE_DEFAULT_VALUE

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor providing a default value for the         |
|               | attribute.                                           |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_default_value**.                         |
+---------------+------------------------------------------------------+
| ***           | This descriptor is conditional.                      |
| Obligation*** |                                                      |
|               | This descriptor must be present if and only if the   |
|               | current described data attribute has its             |
|               | **attribute_obligation** descriptor equal to         |
|               | '**defaulted**' except in the case of a composite    |
|               | attribute, that is for an attribute whose            |
|               | attribute_value_type is a List, or a Choice, where   |
|               | it must be omitted.                                  |
+---------------+------------------------------------------------------+
| ***Descriptor | The format of this descriptor must conform to the    |
| Type***       | type of the attribute that it illustrates, i.e.,     |
|               | must be compliant with the value of the descriptor   |
|               | **attribute_value_type**.                            |
+---------------+------------------------------------------------------+

## ATTRIBUTE_VALUE_EXAMPLE

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor providing examples for the value of the   |
|               | attribute.                                           |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_value_example**.                         |
+---------------+------------------------------------------------------+
| ***           | This descriptor is optional.                         |
| Obligation*** |                                                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is of type **Text**.    |
| Type***       |                                                      |
+---------------+------------------------------------------------------+
|               |                                                      |
+---------------+------------------------------------------------------+
| ***Int        | The text may contain examples and explanatory        |
| eroperability | information. Therefore, it can be of a significant   |
| Constraint*** | length.                                              |
|               |                                                      |
|               | The maximum length for the value of this descriptor  |
|               | is 8000 characters.                                  |
+---------------+------------------------------------------------------+

## ATTRIBUTE_SCOPE

+---------------+------------------------------------------------------+
| ***Purpose*** | Descriptor specifying the category of entities in    |
|               | which the attribute may appear.                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The standard term to be used for this descriptor is  |
| Name***       | **attribute_scope**.                                 |
+---------------+------------------------------------------------------+
| ***           | This descriptor is defaulted.                        |
| Obligation*** |                                                      |
+---------------+------------------------------------------------------+
| ***Descriptor | The value of this descriptor is of type Enumerated   |
| Type***       | with three discrete values: **data**, **dictionary** |
|               | and **all**.                                         |
|               |                                                      |
|               | -   **data**: means that the attribute may appear    |
|               |     only as a data entity attribute;                 |
|               |                                                      |
|               | -   **dictionary**: means that the attribute may     |
|               |     appear only as a data entity dictionary          |
|               |     attribute and is applicable to the entire        |
|               |     collection of data entities in the dictionary;   |
|               |                                                      |
|               | -   **all**: means that the attribute may appear as  |
|               |     a data entity attribute as well as a data entity |
|               |     dictionary attribute, in which case the value in |
|               |     the data entity definition takes precedence.     |
+---------------+------------------------------------------------------+
| ***Default    | data                                                 |
| value***      |                                                      |
+---------------+------------------------------------------------------+
|               |                                                      |
+---------------+------------------------------------------------------+
| ***Int        | The coding values are respectively 'data',           |
| eroperability | 'dictionary' and 'all'.                              |
| Constraint*** |                                                      |
|               | These values are not case-sensitive.                 |
+---------------+------------------------------------------------------+

# Number range ExampleNumber range FigureNumber range TableDATA ENTITY ATTRIBUTES AND DATA ENTITY DICTIONARY ATTRIBUTES

## CONCEPT DEFINITIONS

### A specification or semantic description of a data entity consists of a set of attributes. {#a-specification-or-semantic-description-of-a-data-entity-consists-of-a-set-of-attributes. .Paragraph-3}

### Some of these attributes which are considered as frequently needed are defined in this Recommendation as **standard attributes** (see 4.2 through 4.4). Additional attributes called **user-defined attributes** may be required according to the user's needs. The standard attributes are of character type, however a user-defined attribute may be a character pointer which may point to other, non-character, data. The method to define user-defined attributes is described in 4.5. {#some-of-these-attributes-which-are-considered-as-frequently-needed-are-defined-in-this-recommendation-as-standard-attributes-see-4.2-through-4.4.-additional-attributes-called-user-defined-attributes-may-be-required-according-to-the-users-needs.-the-standard-attributes-are-of-character-type-however-a-user-defined-attribute-may-be-a-character-pointer-which-may-point-to-other-non-character-data.-the-method-to-define-user-defined-attributes-is-described-in-4.5. .Paragraph-3}

### A **data entity** **dictionary** is a collection of data entity descriptions. In this view, a dictionary can be seen as a '**dictionary entity**' that will also be described with attributes (called **dictionary** **attributes**). {#a-data-entity-dictionary-is-a-collection-of-data-entity-descriptions.-in-this-view-a-dictionary-can-be-seen-as-a-dictionary-entity-that-will-also-be-described-with-attributes-called-dictionary-attributes. .Paragraph-3}

### Standard attributes will be used to describe: {#standard-attributes-will-be-used-to-describe .Paragraph-3}

-   some features of the dictionary as a whole (see 4.3);

-   the data entities in the dictionary (see 4.4).

### Three classes of data entities are defined: {#three-classes-of-data-entities-are-defined .Paragraph-3}

-   **model**: a data entity described independently from any instance
    in a data product (e.g., in a 'domain' dictionary), and
    corresponding to a re-usable data entity model from which other data
    entities may inherit the attributes and apply some specialization
    rules;

-   **data field**: a data entity in a data product, having its own
    specific attributes;

-   **constant**: a named constant value used within a dictionary but
    not being part of the data themselves. Such a class enables data
    entity dictionaries to specify values which will be used by several
    projects or within a domain (astronomy constants, image size, etc.).

### It is important to make clear in a dictionary what is the class of the defined entities, as these entities will be used differently according to their class, although they will be described with the same attributes. {#it-is-important-to-make-clear-in-a-dictionary-what-is-the-class-of-the-defined-entities-as-these-entities-will-be-used-differently-according-to-their-class-although-they-will-be-described-with-the-same-attributes. .Paragraph-3}

### The standard attributes are described using the descriptors previously defined and can be: {#the-standard-attributes-are-described-using-the-descriptors-previously-defined-and-can-be .Paragraph-3}

-   **mandatory:** always required;

-   **conditional**: required under specified conditions;

-   **optional**: allowed but not required;

-   **defaulted**: provides a default value for the attribute when the
    attribute is omitted.

### These attributes are classified into five categories: {#these-attributes-are-classified-into-five-categories .Paragraph-3}

-   **identifying attributes** that are applicable for the
    identification of data or dictionary entities;

-   **definitional attributes** that describe core semantic aspects of
    data or dictionary entities;

-   **relational attributes** that describe associations among data or
    dictionary entities;

-   **representational attributes** that describe interpretational
    aspects of data or dictionary entities;

-   **administrative attributes** that describe management and control
    aspects of dictionary entities.

## GENERAL VIEW OF THE STANDARD ATTRIBUTES

### STANDARD ATTRIBUTES FOR DATA ENTITY DICTIONARIES

Table 4-1 provides for each category the standard attributes defined by
this Recommendation for a Data Entity Dictionary. They are applicable to
the entire collection of data entities in the dictionary. The obligation
column indicates whether an attribute is mandatory (M), conditional (C),
optional (O) or defaulted (D).

Table 4-1: Data Entity Dictionary
Attributes[]{#__RefHeading___Toc492883758 .anchor}1

  ------------------- -------------------------------------- ----------------
  **Attribute         **Name of data entity attribute**      **Obligation**
  Category**                                                 

  Identifying         DICTIONARY_NAME                        M

  Definitional        DICTIONARY_DEFINITION                  O

  Relational          EXTERNAL_DICTIONARY_REFERENCE          C

  Representational    TEXT_FIELD_CHARACTER_SET               M

                      CASE_SENSITIVITY                       D

                      LANGUAGE                               M

  Administrative      DICTIONARY_VERSION                     O

                      DICTIONARY_IDENTIFIER                  O

                      DEDSL_VERSION                          M
  ------------------- -------------------------------------- ----------------

###  STANDARD ATTRIBUTES FOR DATA ENTITIES

Table 4-2 provides gives for each category the standard attributes that
are defined by this Recommendation for data entities. The obligation
column indicates whether an attribute is mandatory (M), conditional (C),
optional (O) or defaulted (D) in the definition of each data entity
appearing in a conforming DED.

Table 4-2: Data Entity Attributes[]{#__RefHeading___Toc492883759
.anchor}2

  -------------------- ---------------------------------- ----------------
  **Attribute          **Name of data entity attribute**  **Obligation**
  Category**                                              

  Identifying          NAME                               M

                       ALIAS                              O

                       CLASS                              D

  Definitional         DEFINITION                         M

                       SHORT_DEFINITION                   O

                       COMMENT                            O

                       UNITS                              C

                       SPECIFIC_INSTANCE                  O

  Relational           INHERITS_FROM                      O

                       COMPONENT                          O

                       KEYWORD                            O

                       RELATION                           O

  Representational     DATA_TYPE                          C

                       ENUMERATION_VALUES                 C

                       ENUMERATION_MEANING                O

                       ENUMERATION_CONVENTION             O

                       RANGE                              O

                       TEXT_SIZE                          C

                       CASE_SENSITIVITY                   O

                       LANGUAGE                           O

                       CONSTANT_VALUE                     C
  -------------------- ---------------------------------- ----------------

## standard ATTRIBUTES for data entity dictionaries

### DICTIONARY_NAME

+--------------------+---+---+------------------------------------------------+
| Attribute_Name     | : | * |                                                |
|                    |   | * |                                                |
|                    |   | d |                                                |
|                    |   | i |                                                |
|                    |   | c |                                                |
|                    |   | t |                                                |
|                    |   | i |                                                |
|                    |   | o |                                                |
|                    |   | n |                                                |
|                    |   | a |                                                |
|                    |   | r |                                                |
|                    |   | y |                                                |
|                    |   | _ |                                                |
|                    |   | n |                                                |
|                    |   | a |                                                |
|                    |   | m |                                                |
|                    |   | e |                                                |
|                    |   | * |                                                |
|                    |   | * |                                                |
+--------------------+---+---+------------------------------------------------+
| At                 | : | H |                                                |
| tribute_Definition |   | u |                                                |
|                    |   | m |                                                |
|                    |   | a |                                                |
|                    |   | n |                                                |
|                    |   | r |                                                |
|                    |   | e |                                                |
|                    |   | a |                                                |
|                    |   | d |                                                |
|                    |   | a |                                                |
|                    |   | b |                                                |
|                    |   | l |                                                |
|                    |   | e |                                                |
|                    |   | n |                                                |
|                    |   | a |                                                |
|                    |   | m |                                                |
|                    |   | e |                                                |
|                    |   | f |                                                |
|                    |   | o |                                                |
|                    |   | r |                                                |
|                    |   | t |                                                |
|                    |   | h |                                                |
|                    |   | e |                                                |
|                    |   | D |                                                |
|                    |   | a |                                                |
|                    |   | t |                                                |
|                    |   | a |                                                |
|                    |   | E |                                                |
|                    |   | n |                                                |
|                    |   | t |                                                |
|                    |   | i |                                                |
|                    |   | t |                                                |
|                    |   | y |                                                |
|                    |   | D |                                                |
|                    |   | i |                                                |
|                    |   | c |                                                |
|                    |   | t |                                                |
|                    |   | i |                                                |
|                    |   | o |                                                |
|                    |   | n |                                                |
|                    |   | a |                                                |
|                    |   | r |                                                |
|                    |   | y |                                                |
+--------------------+---+---+------------------------------------------------+
| At                 | : | M |                                                |
| tribute_Obligation |   | a |                                                |
|                    |   | n |                                                |
|                    |   | d |                                                |
|                    |   | a |                                                |
|                    |   | t |                                                |
|                    |   | o |                                                |
|                    |   | r |                                                |
|                    |   | y |                                                |
+--------------------+---+---+------------------------------------------------+
| At                 | : | * |                                                |
| tribute_Value_Type |   | * |                                                |
|                    |   | I |                                                |
|                    |   | d |                                                |
|                    |   | e |                                                |
|                    |   | n |                                                |
|                    |   | t |                                                |
|                    |   | i |                                                |
|                    |   | f |                                                |
|                    |   | i |                                                |
|                    |   | e |                                                |
|                    |   | r |                                                |
|                    |   | * |                                                |
|                    |   | * |                                                |
+--------------------+---+---+------------------------------------------------+
| A                  | : |   | 1                                              |
| ttribute_Maximum\_ |   |   |                                                |
| Occurrence         |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| Att                | : |   | Not_inheritable                                |
| ribute_Inheritance |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| Attribute_Scope    | : |   | dictionary                                     |
+--------------------+---+---+------------------------------------------------+
|                    |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| *                  |   |   |                                                |
| **Interoperability |   |   |                                                |
| Constraints***     |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| Attr               | : |   | 400                                            |
| ibute_Maximum_Size |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| Attribute_Comment  | : |   | The Identifier shall not contain any white     |
|                    |   |   | spaces (e.g., one or more space characters,    |
|                    |   |   | carriage returns, line feeds, form feeds or    |
|                    |   |   | tabs).                                         |
|                    |   |   |                                                |
|                    |   |   | It shall begin with a letter and may be        |
|                    |   |   | followed by letters, digits or the underline   |
|                    |   |   | character.                                     |
|                    |   |   |                                                |
|                    |   |   | It shall end with a letter or a digit.         |
|                    |   |   |                                                |
|                    |   |   | It shall only contain characters in a visibly  |
|                    |   |   | displayable form.                              |
+--------------------+---+---+------------------------------------------------+

### DICTIONARY_DEFINITION

  ------------------------ --- --------------------------- ------------------------------------------------
  Attribute_Name           :   **dictionary_definition**   

  Attribute_Definition     :   Human readable definition   
                               for the Data Entity         
                               Dictionary                  

  Attribute_Obligation     :   Optional                    

  Attribute_Value_Type     :   **Text**                    

  Attribute_Maximum\_      :                               1
  Occurrence                                               

  Attribute_Inheritance    :                               Not_inheritable

  Attribute_Scope          :                               dictionary

  Attribute_Comment        :   The value of this attribute 
                               is a free format text which 
                               can span a number of lines. 

                                                           

  ***Interoperability                                      
  Constraint***                                            

  Attribute_Maximum_Size   :                               8000
  ------------------------ --- --------------------------- ------------------------------------------------

### EXTERNAL_DICTIONARY_REFERENCE

+--------------------+---+---+------------------------------------------------+
| Attribute_Name     | : | * |                                                |
|                    |   | * |                                                |
|                    |   | e |                                                |
|                    |   | x |                                                |
|                    |   | t |                                                |
|                    |   | e |                                                |
|                    |   | r |                                                |
|                    |   | n |                                                |
|                    |   | a |                                                |
|                    |   | l |                                                |
|                    |   | _ |                                                |
|                    |   | d |                                                |
|                    |   | i |                                                |
|                    |   | c |                                                |
|                    |   | t |                                                |
|                    |   | i |                                                |
|                    |   | o |                                                |
|                    |   | n |                                                |
|                    |   | a |                                                |
|                    |   | r |                                                |
|                    |   | y |                                                |
|                    |   | _ |                                                |
|                    |   | r |                                                |
|                    |   | e |                                                |
|                    |   | f |                                                |
|                    |   | e |                                                |
|                    |   | r |                                                |
|                    |   | e |                                                |
|                    |   | n |                                                |
|                    |   | c |                                                |
|                    |   | e |                                                |
|                    |   | * |                                                |
|                    |   | * |                                                |
+--------------------+---+---+------------------------------------------------+
| At                 | : | T |                                                |
| tribute_Definition |   | h |                                                |
|                    |   | i |                                                |
|                    |   | s |                                                |
|                    |   | a |                                                |
|                    |   | t |                                                |
|                    |   | t |                                                |
|                    |   | r |                                                |
|                    |   | i |                                                |
|                    |   | b |                                                |
|                    |   | u |                                                |
|                    |   | t |                                                |
|                    |   | e |                                                |
|                    |   | g |                                                |
|                    |   | i |                                                |
|                    |   | v |                                                |
|                    |   | e |                                                |
|                    |   | s |                                                |
|                    |   | a |                                                |
|                    |   | r |                                                |
|                    |   | e |                                                |
|                    |   | f |                                                |
|                    |   | e |                                                |
|                    |   | r |                                                |
|                    |   | e |                                                |
|                    |   | n |                                                |
|                    |   | c |                                                |
|                    |   | e |                                                |
|                    |   | t |                                                |
|                    |   | o |                                                |
|                    |   | a |                                                |
|                    |   | n |                                                |
|                    |   | o |                                                |
|                    |   | t |                                                |
|                    |   | h |                                                |
|                    |   | e |                                                |
|                    |   | r |                                                |
|                    |   | D |                                                |
|                    |   | a |                                                |
|                    |   | t |                                                |
|                    |   | a |                                                |
|                    |   | E |                                                |
|                    |   | n |                                                |
|                    |   | t |                                                |
|                    |   | i |                                                |
|                    |   | t |                                                |
|                    |   | y |                                                |
|                    |   | D |                                                |
|                    |   | i |                                                |
|                    |   | c |                                                |
|                    |   | t |                                                |
|                    |   | i |                                                |
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|                    |   | n |                                                |
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+--------------------+---+---+------------------------------------------------+
| At                 | : | C |                                                |
| tribute_Obligation |   | o |                                                |
|                    |   | n |                                                |
|                    |   | d |                                                |
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|                    |   | i |                                                |
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|                    |   | n |                                                |
|                    |   | a |                                                |
|                    |   | l |                                                |
+--------------------+---+---+------------------------------------------------+
| At                 | : | * |                                                |
| tribute_Value_Type |   | * |                                                |
|                    |   | L |                                                |
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|                    |   | ( |                                                |
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|                    |   | * |                                                |
|                    |   | * |                                                |
+--------------------+---+---+------------------------------------------------+
| A                  | : |   | 'n'                                            |
| ttribute_Maximum\_ |   |   |                                                |
| Occurrence         |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| A                  | : |   | This attribute is mandatory if a reference to  |
| ttribute_Condition |   |   | a Data Entity Dictionary is made in the        |
|                    |   |   | current data entity dictionary (in one of the  |
|                    |   |   | 'inherits_from' or 'relation' attributes).     |
+--------------------+---+---+------------------------------------------------+
| Attri              | : |   | (CDPP_Plasma_Dictionary, FCST0172,             |
| bute_Value_Example |   |   | CCSDS_Control_Authority)                       |
+--------------------+---+---+------------------------------------------------+
| Att                | : |   | Not_inheritable                                |
| ribute_Inheritance |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| Attribute_Scope    | : |   | dictionary                                     |
+--------------------+---+---+------------------------------------------------+
|                    |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| *                  |   |   |                                                |
| **Interoperability |   |   |                                                |
| Constraints***     |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| Attr               | : |   | **List** (400, 400, 400)                       |
| ibute_Maximum_Size |   |   |                                                |
+--------------------+---+---+------------------------------------------------+
| Attribute_Comment  | : |   | The interoperability constraints defined in    |
|                    |   |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+---+------------------------------------------------+

### TEXT_FIELD_CHARACTER_SET

  ------------------------ --- ------------------------------------------------
  Attribute_Name           :   **text_field_character_set**

  Attribute_Definition     :   Name of the Character Set that is valid for TEXT
                               descriptor type and TEXT attribute value type
                               within the dictionary

  Attribute_Obligation     :   Mandatory

  Attribute_Value_Type     :   **Text**

  Attribute_Maximum\_      :   1
  Occurrence                   

  Attribute_Inheritance    :   Not_inheritable

  Attribute_Scope          :   dictionary

                               

  ***Interoperability          
  Constraint***                

  Attribute_Maximum_Size   :   40
  ------------------------ --- ------------------------------------------------

### CASE_SENSITIVITY

  ------------------------- --- ------------------------------------------------
  Attribute_Name            :   **case_sensitivity**

  Attribute_Definition      :   The value of this attribute specifies the case
                                sensitivity for the Identifiers used as values
                                for the attributes of the current entity. When
                                used in a data entity, the value of the
                                attribute overrides the value specified at the
                                dictionary level.

  Attribute_Obligation      :   Defaulted

  Attribute_Value_Type      :   **Enumerated**

  Attribute_Enumeration\_   :   **(case_sensitive, not_case_sensitive)**
  Values                        

  Attribute_Default_Value   :   not_case_sensitive

  Attribute_Maximum\_       :   1
  Occurrence                    

  Attribute_Inheritance     :   Not_inheritable

  Attribute_Scope           :   all
  ------------------------- --- ------------------------------------------------

### LANGUAGE

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **language**                                   |
+--------------------+---+------------------------------------------------+
| At                 | : | Main natural language that is valid for any    |
| tribute_Definition |   | value of type TEXT given to the attributes of  |
|                    |   | the current entity. When used in a data        |
|                    |   | entity, the value of the attribute overrides   |
|                    |   | the value specified for the dictionary entity. |
+--------------------+---+------------------------------------------------+
| At                 | : | Mandatory                                      |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **List(Text, Identifier)** where:              |
| tribute_Value_Type |   |                                                |
|                    |   | -   text is provided in English and            |
|                    |   |     corresponds to the English name of the     |
|                    |   |     language as specified in ISO 639-2 (see    |
|                    |   |     reference \[5\]);                          |
|                    |   |                                                |
|                    |   | -   identifier refers to a 2 or 3 letter       |
|                    |   |     country code as specified in ISO 639-2.    |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Att                | : | Not_inheritable                                |
| ribute_Inheritance |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | ('French', fr)                                 |
| bute_Value_Example |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Scope    | : | all                                            |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraints***     |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | **List**(40, 3)                                |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

### DICTIONARY_VERSION

  ------------------------- --- ------------------------------------------------
  Attribute_Name            :   **dictionary_version**

  Attribute_Definition      :   Version of the Data Entity Dictionary

  Attribute_Obligation      :   Optional

  Attribute_Value_Type      :   **Text**

  Attribute_Maximum\_       :   1
  Occurrence                    

  Attribute_Comment         :   It corresponds to the issue and the revision of
                                the current dictionary separated by a period.

  Attribute_Value_Example   :   '1.a'

  Attribute_Inheritance     :   Not_inheritable

  Attribute_Scope           :   dictionary
  ------------------------- --- ------------------------------------------------

###  DICTIONARY_IDENTIFIER

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **dictionary_identifier**                      |
+--------------------+---+------------------------------------------------+
| At                 | : | The Identifier under which the Data Entity     |
| tribute_Definition |   | Dictionary has been registered at a            |
|                    |   | registration Authority.                        |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **Identifier**                                 |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Att                | : | Not_inheritable                                |
| ribute_Inheritance |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Scope    | : | dictionary                                     |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraints***     |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | 400                                            |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | If the registration authority is the CCSDS     |
|                    |   | Control Authority (see references \[4\] and    |
|                    |   | \[C-5\]), the format of this attribute value   |
|                    |   | is an unquoted ASCII string of eight           |
|                    |   | consecutive Restricted ASCII characters that   |
|                    |   | constitute a registered MACAO ADID. In case of |
|                    |   | other registration authorities, the attribute  |
|                    |   | value follows the internal registration        |
|                    |   | identification system of the authority.        |
|                    |   |                                                |
|                    |   | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

###  DEDSL_VERSION

  ------------------------- --- ------------------------------------------------
  Attribute_Name            :   **dedsl_version**

  Attribute_Definition      :   CCSDS document number of the document
                                corresponding to the implementation of the
                                Abstract Syntax. Note that this reference
                                contains the version.

  Attribute_Obligation      :   Mandatory

  Attribute_Value_Type      :   **Text**

  Attribute_Maximum\_       :   1
  Occurrence                    

  Attribute_Value_Example   :   'CCSDS 647.2-B-1.0'

  Attribute_Comment         :   For example, a PVL or XML implementation.

  Attribute_Inheritance     :   Not_inheritable

  Attribute_Scope           :   dictionary
  ------------------------- --- ------------------------------------------------

##  STANDARD ATTRIBUTES FOR DATA ENTITIES

### IDENTIFYING ATTRIBUTES

#### Name

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **Name**                                       |
+--------------------+---+------------------------------------------------+
| At                 | : | The value of this attribute may be used to     |
| tribute_Definition |   | link a collection of attributes with an        |
|                    |   | equivalent identifier in, or associated with,  |
|                    |   | the data entity.                               |
|                    |   |                                                |
|                    |   | The value of this attribute may also be used   |
|                    |   | by the software developer to name              |
|                    |   | corresponding variables in software code or    |
|                    |   | designate a field to be searched for locating  |
|                    |   | particular data entities.                      |
|                    |   |                                                |
|                    |   | The **name** shall be unique within a Data     |
|                    |   | Entity Dictionary.                             |
+--------------------+---+------------------------------------------------+
| At                 | : | Mandatory                                      |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **Identifier**                                 |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | ACQ_STATION                                    |
| bute_Value_Example |   |                                                |
+--------------------+---+------------------------------------------------+
| Att                | : | Not_inheritable                                |
| ribute_Inheritance |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraints***     |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | 400                                            |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The interoperability constraints defined in    |
|                    |   | 4.3.1. relative to Identifiers also apply      |
|                    |   | here.                                          |
+--------------------+---+------------------------------------------------+

####  Alias

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **Alias**                                      |
+--------------------+---+------------------------------------------------+
| At                 | : | Single- or multi-word designation that differs |
| tribute_Definition |   | from the given name, but represents the same   |
|                    |   | data entity concept, followed by the context   |
|                    |   | in which this name is applied.                 |
|                    |   |                                                |
|                    |   | The value of this attribute provides an        |
|                    |   | alternative designation of the data entity     |
|                    |   | that may be required for the purpose of        |
|                    |   | compatibility with historical data or data     |
|                    |   | deriving from different sources. For example,  |
|                    |   | different sources may produce data including   |
|                    |   | the same entities, but giving them different   |
|                    |   | names. Through the use of this attribute it    |
|                    |   | will be possible to define the semantic        |
|                    |   | information only once. Along with the          |
|                    |   | alternative designation, this attribute value  |
|                    |   | shall provide a description of the context of  |
|                    |   | when the alternative designation is used.      |
|                    |   |                                                |
|                    |   | The value of the alternative designation can   |
|                    |   | also be searched when a designation used in a  |
|                    |   | corresponding syntax description is not found  |
|                    |   | within the **NAME** values.                    |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **List(Text, Text)**                           |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | 'n'                                            |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | ('TIME_LINE', 'used within the ground          |
| bute_Value_Example |   | segment')                                      |
+--------------------+---+------------------------------------------------+
| Att                | : | Not_inheritable                                |
| ribute_Inheritance |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               |   | **List**(400, 400)                             |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+

#### Class

  ------------------------- --- ------------------------------------------------
  Attribute_Name            :   **class**

  Attribute_Definition      :   The value of this attribute makes a clear
                                statement of what kind of entity is defined by
                                the current entity definition. This definition
                                can be a model definition, a data field
                                definition, or a constant definition.

  Attribute_Obligation      :   Defaulted

  Attribute_Value_Type      :   **Enumerated**

  Attribute_Enumeration\_   :   **(model, data_field, constant)**
  Values                        

  Attribute_Maximum\_       :   1
  Occurrence                    

  Attribute_Inheritance     :   Not_inheritable

  Attribute_Default_Value   :   data_field
  ------------------------- --- ------------------------------------------------

###  DEFINITIONAL ATTRIBUTES

#### Definition

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **definition**                                 |
+--------------------+---+------------------------------------------------+
| At                 | : | Statement that expresses the essential nature  |
| tribute_Definition |   | of a data entity and permits its               |
|                    |   | differentiation from all the other data        |
|                    |   | entities.                                      |
|                    |   |                                                |
|                    |   | This attribute is intended for human           |
|                    |   | readership and therefore any information that  |
|                    |   | will increase the understanding of the         |
|                    |   | identified data entity should be included.     |
|                    |   |                                                |
|                    |   | It is intended that the value of this          |
|                    |   | attribute can be of significant length and     |
|                    |   | hence provide a description of the data entity |
|                    |   | as complete as possible. The value of this     |
|                    |   | attribute can be used as a field to be         |
|                    |   | searched for locating particular data          |
|                    |   | entities.                                      |
+--------------------+---+------------------------------------------------+
| At                 | : | Mandatory                                      |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **Text**                                       |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The value of this attribute may include the    |
|                    |   | same semantic information in natural language  |
|                    |   | as the one carried in a more formal manner by  |
|                    |   | other attributes. This is neither a            |
|                    |   | requirement nor illegal, but the user must     |
|                    |   | make sure that inconsistencies do not arise.   |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | 8000                                           |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+

####  Short_Definition

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **short_definition**                           |
+--------------------+---+------------------------------------------------+
| At                 | : | Statement that expresses the essential nature  |
| tribute_Definition |   | of a data entity in a shorter and more concise |
|                    |   | manner than the statement of the mandatory     |
|                    |   | attribute: **definition**.                     |
|                    |   |                                                |
|                    |   | This attribute provides a summary of the more  |
|                    |   | detailed information provided by the           |
|                    |   | **definition** attribute.                      |
|                    |   |                                                |
|                    |   | The value of this attribute can be used as a   |
|                    |   | field to be searched for locating particular   |
|                    |   | data entities. It is also intended to be used  |
|                    |   | for display purposes by automated software,    |
|                    |   | where the complete definition value would be   |
|                    |   | too long to be presented in a convenient       |
|                    |   | manner to users.                               |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **Text**                                       |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | 80                                             |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+

####  Comment

  ------------------------ --- ------------------------------------------------
  Attribute_Name           :   **comment**

  Attribute_Definition     :   Associated information about a data entity. It
                               enables to add information which does not
                               correspond to definition information.

  Attribute_Obligation     :   Optional

  Attribute_Value_Type     :   **Text**

  Attribute_Maximum\_      :   'n'
  Occurrence                   

                               

  ***Interoperability          
  Constraint***                

  Attribute_Maximum_Size   :   8000
  ------------------------ --- ------------------------------------------------

#### Units

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **units**                                      |
+--------------------+---+------------------------------------------------+
| At                 | : | Attribute that specifies the scientific units  |
| tribute_Definition |   | that should be associated with the value of    |
|                    |   | the data entity so as to make the value        |
|                    |   | meaningful to applications.                    |
+--------------------+---+------------------------------------------------+
| At                 | : | Conditional                                    |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | If the data entity is non-scalar then the      |
| ttribute_Condition |   | attribute shall not be specified. If the data  |
|                    |   | entity is of a scientific scalar type (Integer |
|                    |   | or Real) then it can appear several times for  |
|                    |   | data entities of class **model** and only once |
|                    |   | for data entities of class **data_field** or   |
|                    |   | **constant**.                                  |
+--------------------+---+------------------------------------------------+
| At                 | : | **Text**                                       |
| tribute_Value_Type |   |                                                |
|                    |   | If the scalar type has no unit, e.g., a ratio, |
|                    |   | then the UNITS attribute should be given a     |
|                    |   | particular value (e.g., NO_UNIT). It is up to  |
|                    |   | the implementation recommendation to define    |
|                    |   | this particular value.                         |
|                    |   |                                                |
|                    |   | The contents of the text must conform to the   |
|                    |   | representation specified in ISO 2955 (see      |
|                    |   | reference \[C-10\]).                           |
|                    |   |                                                |
|                    |   | As detailed in ISO 2955, the following         |
|                    |   | conventions apply when combining units:        |
|                    |   |                                                |
|                    |   | -   multiplication shall be indicated by a     |
|                    |   |     period (.), e.g., Pa.s to designate Pascal |
|                    |   |     second, the unit of dynamic viscosity;     |
|                    |   |                                                |
|                    |   | -   negative exponents shall be indicated by   |
|                    |   |     following the unit directly with the       |
|                    |   |     numeric power preceded by a minus sign,    |
|                    |   |     e.g., m-3 to designate m^-3^;              |
|                    |   |                                                |
|                    |   | -   Division shall be indicated by a solidus   |
|                    |   |     (/), e.g., m/s, or by expressing the       |
|                    |   |     denominator with a negative exponent,      |
|                    |   |     e.g., m.s-1;                               |
|                    |   |                                                |
|                    |   | -   Positive exponents shall be indicated by   |
|                    |   |     following the unit directly with the       |
|                    |   |     numeric power with no sign, e.g., m2 to    |
|                    |   |     designate m^2^                             |
|                    |   |                                                |
|                    |   | Decimal multiples of units shall be indicated  |
|                    |   | by the combination of a prefix representation  |
|                    |   | (see reference \[C9\]) immediately before the  |
|                    |   | unit, e.g., kN to represent kilo Newtons.      |
+--------------------+---+------------------------------------------------+
| A                  | : | 'n'                                            |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | 80\.                                           |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+

#### Specific_Instance

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **specific_instance**                          |
+--------------------+---+------------------------------------------------+
| At                 | : | Attribute that provides a real-world meaning   |
| tribute_Definition |   | for a specific instance (a value) of the data  |
|                    |   | entity being described. The reason for         |
|                    |   | providing this information is so that the user |
|                    |   | can see that there is some specific meaning    |
|                    |   | associated with a particular value instance    |
|                    |   | that indicates something more than just the    |
|                    |   | abstract value. For example, the fact that     |
|                    |   | zero degree latitude is the equator could be   |
|                    |   | defined. This means that the value of this     |
|                    |   | attribute must provide both an instance of the |
|                    |   | entity value and a definition of its specific  |
|                    |   | meaning.                                       |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **List(Entity_Type, Text)**                    |
| tribute_Value_Type |   |                                                |
|                    |   | There shall be two values associated with this |
|                    |   | attribute: an instance value (a literal or a   |
|                    |   | constant name) and a specific meaning          |
|                    |   | definition.                                    |
+--------------------+---+------------------------------------------------+
| A                  | : | 'n'                                            |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The values of the attribute can be used to     |
|                    |   | enhance user interfaces and, therefore, user   |
|                    |   | understanding.                                 |
+--------------------+---+------------------------------------------------+
| Attri              | : | A specific value of DEGREE (with the           |
| bute_Value_Example |   | Entity_Type of Real), could be:                |
|                    |   |                                                |
|                    |   | (0.0, 'Greenwich').                            |
+--------------------+---+------------------------------------------------+
| Att                | : | Not_inheritable                                |
| ribute_Inheritance |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | **List**( 80, 400)                             |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+

### RELATIONAL ATTRIBUTES 

#### Inherits_From

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **inherits_from**                              |
+--------------------+---+------------------------------------------------+
| At                 | : | Gives the name of a model or data field from   |
| tribute_Definition |   | which the current entity description inherits  |
|                    |   | attributes. This name must be the value of the |
|                    |   | **name** attribute found in the referred       |
|                    |   | entity description.                            |
|                    |   |                                                |
|                    |   | Referencing this data entity description means |
|                    |   | that all the values of its attributes having   |
|                    |   | their **attribute_inheritance** set to         |
|                    |   | **inheritable** apply to the current           |
|                    |   | description.                                   |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **Choice(Identifier** **, List(Identifier ,    |
| tribute_Value_Type |   | Identifier**))                                 |
|                    |   |                                                |
|                    |   | The first identifier refers to the name of a   |
|                    |   | model or data field.                           |
|                    |   |                                                |
|                    |   | The second one gives the local name of the     |
|                    |   | external Data Entity Dictionary where the      |
|                    |   | referred entity description is defined.        |
|                    |   |                                                |
|                    |   | The absence of the second identifier assumes   |
|                    |   | that this referred model or data field is      |
|                    |   | local to the current Data Entity Dictionary    |
|                    |   | or, if not, that it is to be found in the      |
|                    |   | dictionary referenced through the              |
|                    |   | **external_dictionary_reference** attribute,   |
|                    |   | which must be unique in that case.             |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | (CCSDS_calendar_time, CCSDS_TIME_CODES)        |
| bute_Value_Example |   |                                                |
+--------------------+---+------------------------------------------------+
| Att                | : | Not_inheritable                                |
| ribute_Inheritance |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraints***     |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | **Choice**(400**,List**(400, 400))             |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | This attribute is intended to enable reuse.    |
|                    |   | Each data entity description referring to the  |
|                    |   | same entity should be qualified using the same |
|                    |   | value of this attribute.                       |
|                    |   |                                                |
|                    |   | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

#### Component

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **component**                                  |
+--------------------+---+------------------------------------------------+
| At                 | : | Name of a component, followed by the number of |
| tribute_Definition |   | times it occurs in the composite data entity.  |
|                    |   | The number of times is specified by a range.   |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **Choice(Identifier, Identifier(a .. b))**     |
| tribute_Value_Type |   |                                                |
|                    |   | Where a is the minimum number of times the     |
|                    |   | component occurs and b is the maximum number   |
|                    |   | of times it occurs.                            |
|                    |   |                                                |
|                    |   | a and b are integer literals or constant       |
|                    |   | names.                                         |
|                    |   |                                                |
|                    |   | The following convention applies: the          |
|                    |   | character 'n' indicates that there is no upper |
|                    |   | limit.                                         |
+--------------------+---+------------------------------------------------+
| A                  | : | 'n'                                            |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraints***     |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | 400                                            |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | This attribute can be used only for composite  |
|                    |   | data entities (arrays, records or lists*).*    |
|                    |   | When a composite data entity has no component  |
|                    |   | defined, it means that they are not known yet, |
|                    |   | and will be specified later.                   |
|                    |   |                                                |
|                    |   | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

####  Keyword

  ------------------------ --- ------------------------------------------------
  Attribute_Name           :   **keyword**

  Attribute_Definition     :   A significant word used for retrieving data
                               entities

  Attribute_Obligation     :   Optional

  Attribute_Value_Type     :   **Text**

  Attribute_Maximum\_      :   'n'
  Occurrence                   

                               

  ***Interoperability          
  Constraints***               

  Attribute_Comment        :   This attribute can be used for recording
                               keywords (search keys) associated with the data
                               entity in question. Indeed, it enables the
                               possibility of defining a particular formalism
                               for the text, and then an automatic processing
                               of the text according to the needs.

  Attribute_Maximum_Size   :   80
  ------------------------ --- ------------------------------------------------

#### Relation

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **relation**                                   |
+--------------------+---+------------------------------------------------+
| At                 | : | This attribute is to be used to express a      |
| tribute_Definition |   | relationship between two entity definitions    |
|                    |   | when this relation cannot be expressed using a |
|                    |   | precise standard relational attribute. In that |
|                    |   | case the relationship is user-defined and      |
|                    |   | expressed using free text.                     |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **Choice(List(Text, Identifier),**             |
| tribute_Value_Type |   | **List(Text, Identifier, Identifier ))**       |
|                    |   | where**:**                                     |
|                    |   |                                                |
|                    |   | -   text provides the reader with the kind of  |
|                    |   |     relation that links the two related        |
|                    |   |     entities;                                  |
|                    |   |                                                |
|                    |   | -   the first Identifier is the name of the    |
|                    |   |     entity in relation with the one being      |
|                    |   |     defined;                                   |
|                    |   |                                                |
|                    |   | -   the second Identifier gives the local name |
|                    |   |     of the dictionary when this entity is      |
|                    |   |     described in an external Data Entity       |
|                    |   |     Dictionary.                                |
+--------------------+---+------------------------------------------------+
| A                  | : | 'n'                                            |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | For example, the fact that a constant data     |
| bute_Value_Example |   | entity is being defined that corresponds to    |
|                    |   | the number of pixels of an image may be        |
|                    |   | expressed as a relationship between that       |
|                    |   | constant and the image (entity W_Image that is |
|                    |   | defined in the Spacecraft_Dictionary           |
|                    |   | dictionary) i.e.:                              |
|                    |   |                                                |
|                    |   | ('size of', W_Image, Spacecraft_Dictionary)    |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraints***     |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | **Choice(List**(8000, 400), **List**(8000,     |
| ibute_Maximum_Size |   | 400, 400**))**                                 |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

### REPRESENTATIONAL ATTRIBUTES

#### Data_Type

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **data_type**                                  |
+--------------------+---+------------------------------------------------+
| At                 | : | It specifies the type of the data entity       |
| tribute_Definition |   | values. This attribute shall have one of the   |
|                    |   | following values: **Enumerated**, **Text**,    |
|                    |   | **Real**, **Integer**, **Composite**.          |
+--------------------+---+------------------------------------------------+
| At                 | : | Conditional                                    |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | This attribute must be present for a product   |
| ttribute_Condition |   | data field definition and for a constant       |
|                    |   | definition (**class** attribute set to         |
|                    |   | **data_field** or **constant**) and is         |
|                    |   | optional for a model definition (**class**     |
|                    |   | attribute set to **model**).                   |
+--------------------+---+------------------------------------------------+
| At                 | : | **Enumerated**                                 |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | (**Enumerated, Text, Real, Integer,            |
| bute_Enumeration\_ |   | Composite**)                                   |
| Values             |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | This attribute defines the conceptual data     |
|                    |   | type of the entity, it is not intended for     |
|                    |   | specifying the physical representation of the  |
|                    |   | entity.                                        |
|                    |   |                                                |
|                    |   | For example, an entity may be defined as an    |
|                    |   | Integer; physically it may be encoded as a     |
|                    |   | 16-bit 2's complement binary number or as an   |
|                    |   | ASCII encoded decimal, but in both cases the   |
|                    |   | **data_type** would be **Integer**.            |
+--------------------+---+------------------------------------------------+

####  Enumeration Attributes

##### General

When a data entity belongs to an enumerated type (attribute
**data_type** set to **Enumerated**), it means that each possible value
of the enumeration has:

-   an enumerated value (an identifier as meaningful as possible);

-   a meaning (which can be expressed in free text);

-   a convention value (corresponding to a human interpretable value for
    the coding of the enumeration value ).

##### Enumeration_Values

  ------------------------- --- ------------------------------------------------
  Attribute_Name            :   **enumeration_values**

  Attribute_Definition      :   The set of permitted values of the
                                **enumerated** data entity.

  Attribute_Obligation      :   Conditional

  Attribute_Condition       :   This attribute is mandatory if the **data_type**
                                is **Enumerated**. It is not applicable in any
                                other case.

  Attribute_Value_Type      :   **List(Identifier)**

  Attribute_Value_Example   :   (NOMINAL, CALIBRATION, OFF)

  Attribute_Maximum\_       :   1
  Occurrence                    

                                

  ***Interoperability           
  Constraint***                 

  Attribute_Comment         :   The interoperability constraints defined in
                                4.3.1 relative to Identifiers also apply here.
  ------------------------- --- ------------------------------------------------

#####  Enumeration_Meaning

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **enumeration_meaning**                        |
+--------------------+---+------------------------------------------------+
| At                 | : | Enables to give a meaning to each value given  |
| tribute_Definition |   | by the attribute enumeration_values.           |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | This attribute is permitted if the             |
| ttribute_Condition |   | **data_type** is **Enumerated**. It is not     |
|                    |   | applicable in any other case.                  |
+--------------------+---+------------------------------------------------+
| At                 | : | **List(List(Identifier,Text))**                |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | ( (NOMINAL, 'equipment on and working'),       |
| bute_Value_Example |   |                                                |
|                    |   | (CALIBRATION , 'equipment under calibration    |
|                    |   | tests'),                                       |
|                    |   |                                                |
|                    |   | (OFF , 'equipment off'))                       |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The identifiers must be identical to the       |
|                    |   | values given in the attribute                  |
|                    |   | ENUMERATION_VALUES.                            |
|                    |   |                                                |
|                    |   | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

#####  Enumeration_Convention

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **enumeration_convention**                     |
+--------------------+---+------------------------------------------------+
| At                 | : | Gives guidance on the correspondence between   |
| tribute_Definition |   | the **enumeration_values** and the numeric or  |
|                    |   | textual values found within the products.      |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | This attribute is permitted if the             |
| ttribute_Condition |   | **data_type** is **Enumerated**. It is not     |
|                    |   | applicable in any other case.                  |
+--------------------+---+------------------------------------------------+
| At                 | : | **List(List(Identifier,Text))**                |
| tribute_Value_Type |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | ((NOMINAL, '0'), (CALIBRATION ,'1'), (OFF ,    |
| bute_Value_Example |   | '2'))                                          |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The identifiers must be identical to the       |
|                    |   | values given in the attribute                  |
|                    |   | ENUMERATION_VALUES.                            |
|                    |   |                                                |
|                    |   | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

####  Range

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **range**                                      |
+--------------------+---+------------------------------------------------+
| At                 | : | The minimum bound and the maximum bound of an  |
| tribute_Definition |   | **Integer** or **Real** data entity            |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **List(Entity_Type, Entity_Type)**             |
| tribute_Value_Type |   |                                                |
|                    |   | The first specified value is the minimum bound |
|                    |   | (literal value or constant name), while the    |
|                    |   | second one is the maximum bound (literal value |
|                    |   | or constant name).                             |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | This attribute only applies for Integer and    |
|                    |   | Real data entities.                            |
+--------------------+---+------------------------------------------------+
| Attri              | : | For a Real data entity called DEGREE, the      |
| bute_Value_Example |   | range could be as follows: (0.0, 360.0).       |
+--------------------+---+------------------------------------------------+

####  Text_Size

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **text_size**                                  |
+--------------------+---+------------------------------------------------+
| At                 | : | The limitation on the size of the values of a  |
| tribute_Definition |   | Text data entity. This attribute specifies the |
|                    |   | minimum and the maximum number of characters   |
|                    |   | the text may contain. If the minimum and the   |
|                    |   | maximum are equal, then this implies that the  |
|                    |   | exact size of the text is known.               |
+--------------------+---+------------------------------------------------+
| At                 | : | Conditional                                    |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| A                  | : | This attribute is mandatory if the             |
| ttribute_Condition |   | **data_type** is **Text**.                     |
+--------------------+---+------------------------------------------------+
| At                 | : | **Choice(Integer**,**List(Integer, Integer))** |
| tribute_Value_Type |   |                                                |
|                    |   | A single integer indicates the maximum only. A |
|                    |   | **List** of two integers denotes the minimum   |
|                    |   | and maximum, in that order. The integer(s) can |
|                    |   | be expressed as a literal value or a constant  |
|                    |   | name.                                          |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraint***      |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here  |
|                    |   | for constant names.                            |
+--------------------+---+------------------------------------------------+

####  Case_Sensitivity

  ------------------------- --- ------------------------------------------------
  Attribute_Name            :   **case_sensitivity**

  Attribute_Definition      :   The value of this attribute specifies the case
                                sensitivity for the Identifiers used as values
                                for the attributes of the current entity. When
                                used in a data entity, the value of the
                                attribute overrides the value specified at the
                                dictionary level.

  Attribute_Obligation      :   Optional

  Attribute_Value_Type      :   **Enumerated**

  Attribute_Enumeration\_   :   **(case_sensitive, not_case_sensitive)**
  Values                        

  Attribute_Maximum\_       :   1
  Occurrence                    

  Attribute_Inheritance     :   Not_inheritable

  Attribute_Scope           :   data
  ------------------------- --- ------------------------------------------------

####  Language

+--------------------+---+------------------------------------------------+
| Attribute_Name     | : | **language**                                   |
+--------------------+---+------------------------------------------------+
| At                 | : | Main natural language that is valid for any    |
| tribute_Definition |   | value of type TEXT given to the attributes of  |
|                    |   | the current entity. When used in a data        |
|                    |   | entity, the value of the attribute overrides   |
|                    |   | the value specified for the dictionary entity. |
+--------------------+---+------------------------------------------------+
| At                 | : | Optional                                       |
| tribute_Obligation |   |                                                |
+--------------------+---+------------------------------------------------+
| At                 | : | **List(Text, Identifier)** where:              |
| tribute_Value_Type |   |                                                |
|                    |   | -   text is provided in English and            |
|                    |   |     corresponds to the English name of the     |
|                    |   |     language as specified in ISO 639-2 (see    |
|                    |   |     reference \[5\]);                          |
|                    |   |                                                |
|                    |   | -   identifier refers to a 2 or 3 letter       |
|                    |   |     country code as specified in ISO 639-2.    |
+--------------------+---+------------------------------------------------+
| A                  | : | 1                                              |
| ttribute_Maximum\_ |   |                                                |
| Occurrence         |   |                                                |
+--------------------+---+------------------------------------------------+
| Att                | : | Not_inheritable                                |
| ribute_Inheritance |   |                                                |
+--------------------+---+------------------------------------------------+
| Attri              | : | ('French', fr)                                 |
| bute_Value_Example |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Scope    | : | data                                           |
+--------------------+---+------------------------------------------------+
|                    |   |                                                |
+--------------------+---+------------------------------------------------+
| *                  |   |                                                |
| **Interoperability |   |                                                |
| Constraints***     |   |                                                |
+--------------------+---+------------------------------------------------+
| Attr               | : | **List**(40, 3)                                |
| ibute_Maximum_Size |   |                                                |
+--------------------+---+------------------------------------------------+
| Attribute_Comment  | : | The interoperability constraints defined in    |
|                    |   | 4.3.1 relative to Identifiers also apply here. |
+--------------------+---+------------------------------------------------+

####  Constant_Value

  ----------------------- --- ------------------------------------------------
  Attribute_Name          :   **constant_value**

  Attribute_Definition    :   The value of this attribute is the value given
                              to a constant (entity whose **class** attribute
                              is set to **constant**).

  Attribute_Obligation    :   Conditional

  Attribute_Condition     :   This attribute is mandatory if **class**
                              attribute is set to **constant**. It is not
                              applicable in any other case.

  Attribute_Value_Type    :   **Entity_Type**

  Attribute_Maximum\_     :   1
  Occurrence                  

  Attribute_Inheritance   :   Not_inheritable
  ----------------------- --- ------------------------------------------------

##  USER-DEFINED ATTRIBUTES

### General

NOTE -- The standard attributes specified in section 4 are those
predefined by this Recommendation and must be recognized by any system
that states conformance to this Recommendation. It is recognized that
there may be further attributes that are more specific to a particular
domain, mission or project.

#### This section defines the mechanism used to define specific attributes; then these attributes can be used in the same manner as the standard ones to define the semantics of particular data entities. These attributes shall be called '**user-defined attributes**'. {#this-section-defines-the-mechanism-used-to-define-specific-attributes-then-these-attributes-can-be-used-in-the-same-manner-as-the-standard-ones-to-define-the-semantics-of-particular-data-entities.-these-attributes-shall-be-called-user-defined-attributes. .Paragraph-4}

#### User-defined attributes shall not have the same name as any standard attribute. {#user-defined-attributes-shall-not-have-the-same-name-as-any-standard-attribute. .Paragraph-4}

### MECHANISM FOR NEW ATTRIBUTE DEFINITIONS

#### A **User-Defined Attribute** is defined using the attribute descriptors specified in section 3. The description of a User-Defined Attribute follows the same rules as the one of a standard attribute. {#a-user-defined-attribute-is-defined-using-the-attribute-descriptors-specified-in-section-3.-the-description-of-a-user-defined-attribute-follows-the-same-rules-as-the-one-of-a-standard-attribute. .Paragraph-4}

#### The mandatory descriptors are: {#the-mandatory-descriptors-are .Paragraph-4}

-   Attribute_Name;

-   Attribute_Definition;

-   Attribute_Obligation;

-   Attribute_Value_Type;

-   Attribute_Maximum_Occurrence.

#### The conditional descriptors are: {#the-conditional-descriptors-are .Paragraph-4}

-   Attribute_Condition;

-   Attribute_Enumeration_Values;

-   Attribute_Default_Value.

#### The optional descriptors are: {#the-optional-descriptors-are .Paragraph-4}

-   Attribute_Maximum_Size;

-   Attribute_Value_Example;

-   Attribute_Comment.

#### The defaulted descriptors are: {#the-defaulted-descriptors-are .Paragraph-4}

-   Attribute_Inheritance;

-   Attribute_Scope.

NOTE -- The following example gives the definition of the user-defined
attribute ASSOCIATED_UTILITIES providing the name of the utility which
processes the physical values of a specific data entity within a data
product.

  ------------------------- --- -------------------------------------------
  Attribute_Name            :   **ASSOCIATED_UTILITIES**

  Attribute_Definition      :   'Attribute that provides the name of the
                                utility used to process the occurrences of
                                the data entity with which the attribute is
                                associated.'

  Attribute_Obligation      :   Optional

  Attribute_Value_Type      :   List(Text, Text)

  Attribute_Comment         :   'The first text gives the name of the
                                utility, and the second one specifies the
                                application context of the utility.'
  ------------------------- --- -------------------------------------------

Example 4-1: Defining User-Defined
Attribute[]{#__RefHeading___Toc493389421 .anchor}1

NOTE -- This second example shows how to define an external reference.

  ------------------------- --- -------------------------------------------
  Attribute_Name            :   **AUDIO_EXAMPLE**

  Attribute_Definition      :   'The AUDIO_EXAMPLE attribute is a pointer
                                to a sound file in .wav format providing an
                                example to be heard'.

  Attribute_Obligation      :   Optional

  Attribute_Value_Type      :   Text

  Attribute_Comment         :   'The value is expressed as a path name'.
  ------------------------- --- -------------------------------------------

Example 4-2: Defining User-Defined Attribute with an External
Reference[]{#__RefHeading___Toc493389422 .anchor}2

NOTE -- The attribute usage in a data entity description would be as
follows:

  ------------------------- --- -------------------------------------------
  NAME                      :   **MUSIC_INSTRUMENT**

  CLASS                     :   Model

  DEFINITION                :   'It corresponds to an instrument'.

  DATA_TYPE                 :   Enumerated

  ENUMERATION_VALUES        :   (Piano, Guitar, Violin, Saxophone)

  AUDIO_EXAMPLE             :   '/home/MUSIC/INSTRUMENTS/SOUND/Piano.wav'
  ------------------------- --- -------------------------------------------

Example 4-3: Usage of a User-Defined
Attribute[]{#__RefHeading___Toc493389423 .anchor}3

### REGISTRATION OF USER-DEFINED ATTRIBUTES

#### So as to obtain maximum reuse and hence interoperability across missions, projects and agencies, it is desirable that new user-defined attributes which are created by projects are submitted for central registration. This means that they can be reused by other projects, eventually leading to a uniform data entity dictionary across many missions and projects. {#so-as-to-obtain-maximum-reuse-and-hence-interoperability-across-missions-projects-and-agencies-it-is-desirable-that-new-user-defined-attributes-which-are-created-by-projects-are-submitted-for-central-registration.-this-means-that-they-can-be-reused-by-other-projects-eventually-leading-to-a-uniform-data-entity-dictionary-across-many-missions-and-projects. .Paragraph-4}

#### The advantage of sharing the data entity dictionary is that software can be developed to handle the entity data descriptions, which can then be reused by many other projects. In addition, labeling and identification information appearing on products coming from different projects will be comparable. {#the-advantage-of-sharing-the-data-entity-dictionary-is-that-software-can-be-developed-to-handle-the-entity-data-descriptions-which-can-then-be-reused-by-many-other-projects.-in-addition-labeling-and-identification-information-appearing-on-products-coming-from-different-projects-will-be-comparable. .Paragraph-4}

#### To register user-defined attributes, the data description registration capabilities detailed in the CCSDS Recommendations on Control Authorities (see references \[4\] and \[C-5\]) should be followed. {#to-register-user-defined-attributes-the-data-description-registration-capabilities-detailed-in-the-ccsds-recommendations-on-control-authorities-see-references-4-and-c-5-should-be-followed. .Paragraph-4}

#### When a user registers a user-defined attribute, the following information must be included: {#when-a-user-registers-a-user-defined-attribute-the-following-information-must-be-included .Paragraph-4}

-   identification of the user---this information shall be as defined in
    the registration of data descriptions with the CCSDS Control
    Authority (see references \[4\] and \[C-5\]);

-   a specification of the user-defined attribute using the descriptors
    defined in section 3;

-   if software is available to support processing of the value of the
    user-defined attribute, this should be submitted with the
    definition, as shown in the previous example for the user-defined
    attribute ASSOCIATED_UTILITIES.

## RELATIONSHIP RULES

### REFERENCE TO AN EXTERNAL Data Entity DICTIONARY

#### As seen previously (in attributes definition), some Data Entity Dictionary references can be made to other Data Entity Dictionaries. {#as-seen-previously-in-attributes-definition-some-data-entity-dictionary-references-can-be-made-to-other-data-entity-dictionaries. .Paragraph-4}

#### In a Data Entity Dictionary definition, the **external_dictionary_reference** attribute can be used (1 to n times, where n means an unspecified number of times) to reference the data entity dictionaries whose data entities are reused in the current one, or whose data entities are referred to in relationships with the current one. {#in-a-data-entity-dictionary-definition-the-external_dictionary_reference-attribute-can-be-used-1-to-n-times-where-n-means-an-unspecified-number-of-times-to-reference-the-data-entity-dictionaries-whose-data-entities-are-reused-in-the-current-one-or-whose-data-entities-are-referred-to-in-relationships-with-the-current-one. .Paragraph-4}

#### When a data entity is reused (as underlined by the use of the **inherits_from** attribute), the origin of this data entity can be given by the second value of this attribute, which matches the local name given in the **external_dictionary_reference**. If this second value is omitted, it means that the description of the reused data entity is assumed to be local to the current data entity dictionary. {#when-a-data-entity-is-reused-as-underlined-by-the-use-of-the-inherits_from-attribute-the-origin-of-this-data-entity-can-be-given-by-the-second-value-of-this-attribute-which-matches-the-local-name-given-in-the-external_dictionary_reference.-if-this-second-value-is-omitted-it-means-that-the-description-of-the-reused-data-entity-is-assumed-to-be-local-to-the-current-data-entity-dictionary. .Paragraph-4}

### COMPOSITION RELATION

#### As seen previously a data entity may be composite, that is, it can be made up of a series of other data entities. This notion is rendered by the composition relation for which the **component** attribute is defined. {#as-seen-previously-a-data-entity-may-be-composite-that-is-it-can-be-made-up-of-a-series-of-other-data-entities.-this-notion-is-rendered-by-the-composition-relation-for-which-the-component-attribute-is-defined. .Paragraph-4}

#### The order of the components in data entities is not significant. {#the-order-of-the-components-in-data-entities-is-not-significant. .Paragraph-4}

#### When a data entity is considered as being composite, it is not obligatory to mention all its component data entities if these are not known yet (in particular, when the dictionary is undergoing a definition process). However, when the data entity dictionary corresponds to a physical data product, the components have to be defined. {#when-a-data-entity-is-considered-as-being-composite-it-is-not-obligatory-to-mention-all-its-component-data-entities-if-these-are-not-known-yet-in-particular-when-the-dictionary-is-undergoing-a-definition-process.-however-when-the-data-entity-dictionary-corresponds-to-a-physical-data-product-the-components-have-to-be-defined. .Paragraph-4}

###  INHERITANCE

#### General

##### A data entity defined with the **class** attribute set to **model** or **data field** can be reused in other data entity descriptions. The **inherits_from** attribute must then be used in the data entity descriptions which wish to reuse that data entity description. {#a-data-entity-defined-with-the-class-attribute-set-to-model-or-data-field-can-be-reused-in-other-data-entity-descriptions.-the-inherits_from-attribute-must-then-be-used-in-the-data-entity-descriptions-which-wish-to-reuse-that-data-entity-description. .Paragraph-5}

##### Only a **model** may be inherited by other **models**. {#only-a-model-may-be-inherited-by-other-models. .Paragraph-5}

##### Once a reference has been made to the referred data entity, the current description will then inherit the values of all the attributes of the referred entity which have been defined as **inheritable**. Moreover, specialization rules apply to inheritable attributes. {#once-a-reference-has-been-made-to-the-referred-data-entity-the-current-description-will-then-inherit-the-values-of-all-the-attributes-of-the-referred-entity-which-have-been-defined-as-inheritable.-moreover-specialization-rules-apply-to-inheritable-attributes. .Paragraph-5}

##### All the identifying attributes of data entities and all the dictionary attributes as well as the attributes **inherits_from** and **specific_instance** are **not_inheritable**. These attributes have to be defined locally in the current data entity or dictionary entity. {#all-the-identifying-attributes-of-data-entities-and-all-the-dictionary-attributes-as-well-as-the-attributes-inherits_from-and-specific_instance-are-not_inheritable.-these-attributes-have-to-be-defined-locally-in-the-current-data-entity-or-dictionary-entity. .Paragraph-5}

#### Specialization Rules for the Inheritable Attributes

##### Specialization of Optional Attributes

Optional attributes may appear a specified number of times. When an
entity inherits from another entity, optional attributes can be present
or not in the referred entity, and they can be added in the current
entity as long as the number of allowed occurrences is not exceeded.

##### Specialization Rules for Various Data_Types

###### Attributes specified in the referred entity may be specialized but not overridden with a different value. The specialization operations allowed for each attribute is based on the descriptor ATTRIBUTE_VALUE_TYPE. It should be noted that no change to an attribute is always considered as a valid specialization. {#attributes-specified-in-the-referred-entity-may-be-specialized-but-not-overridden-with-a-different-value.-the-specialization-operations-allowed-for-each-attribute-is-based-on-the-descriptor-attribute_value_type.-it-should-be-noted-that-no-change-to-an-attribute-is-always-considered-as-a-valid-specialization. .Paragraph-6}

###### Values of attributes of type **Integer** or **Real** can be specialized by limiting the range of the value domain defined at the referred entity. {#values-of-attributes-of-type-integer-or-real-can-be-specialized-by-limiting-the-range-of-the-value-domain-defined-at-the-referred-entity. .Paragraph-6}

###### Values of attributes of type **Identifier** cannot be specialized; they must be identical to the value given in the referred entity. {#values-of-attributes-of-type-identifier-cannot-be-specialized-they-must-be-identical-to-the-value-given-in-the-referred-entity. .Paragraph-6}

###### Values of attributes of type **Text** can be specialized by adding text (no deletions) to the value given in the referred entity. {#values-of-attributes-of-type-text-can-be-specialized-by-adding-text-no-deletions-to-the-value-given-in-the-referred-entity. .Paragraph-6}

###### Values of attributes of type **Enumerated** can be specialized by removing some **enumeration_values** and the corresponding **enumeration_meaning** and **enumeration_convention**. {#values-of-attributes-of-type-enumerated-can-be-specialized-by-removing-some-enumeration_values-and-the-corresponding-enumeration_meaning-and-enumeration_convention. .Paragraph-6}

###### Values of attributes of type **Entity_Type** cannot be specialized and must be identical to the value given in the referred entity. {#values-of-attributes-of-type-entity_type-cannot-be-specialized-and-must-be-identical-to-the-value-given-in-the-referred-entity. .Paragraph-6}

###### Values of attributes of type **Choice** can be specialized by removing some elementary types from the set of elementary types of the referred entity. {#values-of-attributes-of-type-choice-can-be-specialized-by-removing-some-elementary-types-from-the-set-of-elementary-types-of-the-referred-entity. .Paragraph-6}

###### Value of attributes of type **List** cannot be specialized. {#value-of-attributes-of-type-list-cannot-be-specialized. .Paragraph-6}

##### Specialization of the Definitional Attributes

###### The attributes DEFINITION, SHORT_DEFINITION and COMMENT can be specialized locally so long as the value enriches the information expressed at the referred entity. {#the-attributes-definition-short_definition-and-comment-can-be-specialized-locally-so-long-as-the-value-enriches-the-information-expressed-at-the-referred-entity. .Paragraph-6}

###### In the case of a **data_field**/**constant/model** inheriting from a model, the following rules apply for the attribute UNITS: {#in-the-case-of-a-data_fieldconstantmodel-inheriting-from-a-model-the-following-rules-apply-for-the-attribute-units .Paragraph-6}

-   if the model has no units attribute, the units attribute of the
    **data_field**/**constant**/**model** is unconstrained;

-   if the model provides units attribute values, the units attribute
    value of the **data_field**/**constant**/**model** must be one of
    those listed in the model.

##### Specialization of the Representational Attributes

###### A **model** does not need to have representational attributes specified. A **data_field** must have them specified. {#a-model-does-not-need-to-have-representational-attributes-specified.-a-data_field-must-have-them-specified. .Paragraph-6}

###### If a **data_field** inherits from a **model** which does not have them specified, then it must specify them locally. {#if-a-data_field-inherits-from-a-model-which-does-not-have-them-specified-then-it-must-specify-them-locally. .Paragraph-6}

###### If a **data_field** inherits from a **model** or a **data_field** which does have them specified, then the above rules of specialization apply. {#if-a-data_field-inherits-from-a-model-or-a-data_field-which-does-have-them-specified-then-the-above-rules-of-specialization-apply. .Paragraph-6}

##### Specialization of the Relational Attributes

###### Relational attributes are inheritable except for the 'INHERITS_FROM' attribute. They can be defined locally and their value enriches the information expressed in the referred entity, since their ATTRIBUTE_VALUE_TYPE is Text. {#relational-attributes-are-inheritable-except-for-the-inherits_from-attribute.-they-can-be-defined-locally-and-their-value-enriches-the-information-expressed-in-the-referred-entity-since-their-attribute_value_type-is-text. .Paragraph-6}

###### As seen in 4.4.3.2., the COMPONENT attribute is inheritable. This attribute can appear any number of times, therefore components can be added to specialize the definition of the data entity with regard to the referred entity. {#as-seen-in-4.4.3.2.-the-component-attribute-is-inheritable.-this-attribute-can-appear-any-number-of-times-therefore-components-can-be-added-to-specialize-the-definition-of-the-data-entity-with-regard-to-the-referred-entity. .Paragraph-6}

### OTHER KINDS OF RELATION

In addition to the relationships handled with a specific attribute (see
above), some other ones have to be described in data entity
dictionaries. In that case, there are two possible ways to proceed:

-   define a precise user-defined attribute with appropriate descriptors
    and use it;

-   use the generic standard relation attribute name 'relation' and
    express the relationship in free text.

# Number range ExampleNumber range FigureNumber range TableIMPLEMENTATION GUIDELINES

NOTE -- This section provides some guidelines concerning the use of
attributes, whether 'standard', or 'user-defined'.

## For any single semantic entity description, the standard attributes can be presented or accessed in any order; however, it is recommended that the following order should be used whenever possible so as to present a common style to all users. The mandatory attributes are indicated in bold characters, while the optional and conditional attributes are in italic characters: {#for-any-single-semantic-entity-description-the-standard-attributes-can-be-presented-or-accessed-in-any-order-however-it-is-recommended-that-the-following-order-should-be-used-whenever-possible-so-as-to-present-a-common-style-to-all-users.-the-mandatory-attributes-are-indicated-in-bold-characters-while-the-optional-and-conditional-attributes-are-in-italic-characters .Paragraph-2}

**NAME\
***ALIAS\
*CLASS**\
DEFINITION\
***SHORT_DEFINITION\
COMMENT\
UNITS\
SPECIFIC_INSTANCE\
INHERITS_FROM\
COMPONENT\
KEYWORD\
RELATION\
DATA_TYPE\
ENUMERATION_VALUES\
ENUMERATION_MEANING\
ENUMERATION_CONVENTION\
RANGE\
TEXT_SIZE\
CASE_SENSITIVITY\
LANGUAGE\
CONSTANT_VALUE*

## User-defined attributes should be placed following the standard attributes. {#user-defined-attributes-should-be-placed-following-the-standard-attributes. .Paragraph-2}

## For any single user-defined attribute definition, the descriptors defining the user-defined attribute can be presented or accessed in any order; however, it is recommended that the following order should be used whenever possible so as to present a common style to all users. The mandatory descriptors are indicated in bold characters, while the optional and conditional descriptors are in italic characters: {#for-any-single-user-defined-attribute-definition-the-descriptors-defining-the-user-defined-attribute-can-be-presented-or-accessed-in-any-order-however-it-is-recommended-that-the-following-order-should-be-used-whenever-possible-so-as-to-present-a-common-style-to-all-users.-the-mandatory-descriptors-are-indicated-in-bold-characters-while-the-optional-and-conditional-descriptors-are-in-italic-characters .Paragraph-2}

**ATTRIBUTE_NAME\
ATTRIBUTE_DEFINITION\
ATTRIBUTE_OBLIGATION*\
****ATTRIBUTE_CONDITION\
***ATTRIBUTE_MAXIMUM_OCCURRENCE***\
***ATTRIBUTE_VALUE_TYPE***\
ATTRIBUTE_MAXIMUM_SIZE\
ATTRIBUTE_ENUMERATION_VALUES\
ATTRIBUTE_COMMENT\
*ATTRIBUTE_INHERITANCE*\
ATTRIBUTE_DEFAULT_VALUE\
ATTRIBUTE_VALUE_EXAMPLE\
*ATTRIBUTE_SCOPE

## The attributes for each entity description (or descriptors for each attribute definition) must be grouped in some manner so as to keep them separate from the attributes of other entity descriptions. The methodology for grouping the attributes must be defined formally in the DEDSL implementation syntax. {#the-attributes-for-each-entity-description-or-descriptors-for-each-attribute-definition-must-be-grouped-in-some-manner-so-as-to-keep-them-separate-from-the-attributes-of-other-entity-descriptions.-the-methodology-for-grouping-the-attributes-must-be-defined-formally-in-the-dedsl-implementation-syntax. .Paragraph-2}

## It is strongly recommended to define a maximum length for identifiers and texts for readability reasons, as well as for possible automatic processing of the DED. {#it-is-strongly-recommended-to-define-a-maximum-length-for-identifiers-and-texts-for-readability-reasons-as-well-as-for-possible-automatic-processing-of-the-ded. .Paragraph-2}

## Although the standard attributes for defining the dictionary can be presented or accessed in any order, it is recommended that the following order should be used whenever possible so as to present a common style to all users. The mandatory descriptors are indicated in bold characters, while the optional and conditional attributes are in italic characters: {#although-the-standard-attributes-for-defining-the-dictionary-can-be-presented-or-accessed-in-any-order-it-is-recommended-that-the-following-order-should-be-used-whenever-possible-so-as-to-present-a-common-style-to-all-users.-the-mandatory-descriptors-are-indicated-in-bold-characters-while-the-optional-and-conditional-attributes-are-in-italic-characters .Paragraph-2}

**DICTIONARY_NAME\
***DICTIONARY_DEFINITION\
EXTERNAL**\_**DICTIONARY\_*REFERENCE***\
*TEXT_FIELD_CHARACTER_SET*\
***CASE_SENSITIVITY***\
*LANGUAGE*\
****DICTIONARY_VERSION**\
**DICTIONARY_IDENTIFIER**\
*****DEDSL_VERSION**

# Number range ExampleNumber range FigureNumber range TableDEDSL CONFORMANCE: ABSTRACT DEDSL (ADID = CCSD0011)

## General

### This DEDSL specification (sections 3 and 4) is version 1.0 of the DEDSL specification Recommendation and defines a set of standard attributes by name, with restrictions on their permitted values. Note that this part of the specification does not specify how the attribute names and values are to be linked to any given data object. This allows a variety of formatting approaches to be used for this linking. {#this-dedsl-specification-sections-3-and-4-is-version-1.0-of-the-dedsl-specification-recommendation-and-defines-a-set-of-standard-attributes-by-name-with-restrictions-on-their-permitted-values.-note-that-this-part-of-the-specification-does-not-specify-how-the-attribute-names-and-values-are-to-be-linked-to-any-given-data-object.-this-allows-a-variety-of-formatting-approaches-to-be-used-for-this-linking. .Paragraph-3}

### A certain number of interoperability constraints appear within this Recommendation. These constraints will increase the likelihood of interoperability between different implementations, resulting in two levels of DEDSL conformance. {#a-certain-number-of-interoperability-constraints-appear-within-this-recommendation.-these-constraints-will-increase-the-likelihood-of-interoperability-between-different-implementations-resulting-in-two-levels-of-dedsl-conformance. .Paragraph-3}

## CONFORMANCE LEVEL 1: BASE COMPLIANCE

Implementations which implement all of sections 3 and 4 of this
Recommendation except the interoperability constraints will be base
compliant with this Recommendation.

## CONFORMANCE LEVEL 2: FULL COMPLIANCE

Implementations which implement all of sections 3 and 4 of this
Recommendation will be fully compliant with this Recommendation.

######## Number range ExampleNumber range FigureNumber range TableNumber range Annex_Level_1  DEDSL EXAMPLES

(This annex **is not** part of the Recommendation)

In this section a community DED is presented showing the semantic
information relative to the data entities chosen as models. Then the
definition of a product DED is given using this community DED for the
definition of some of its data entities.

######## COMMUNITY DED {#community-ded .Annex-2}

**a) Data Entity Dictionary attributes**

  ------------------------------ --- ---------------------------------------
  DICTIONARY_NAME                :   Planetary_Science_Data_Dictionary

  DICTIONARY_DEFINITION          :   'This dictionary contains data entity
                                     definitions relative to planetary
                                     science and which may be re-used for
                                     defining data products.'

  TEXT_FIELD_CHARACTER_SET       :   'ISO-LATIN ALPHABET No1'

  CASE_SENSITIVITY               :   NOT_CASE_SENSITIVE

  LANGUAGE                       :   ('English', en)

  DICTIONARY_VERSION             :   '1.a'

  DEDSL_VERSION                  :   'CCSDS 647.2-B-1.0'
  ------------------------------ --- ---------------------------------------

b\) Data Entities

  ------------------------------ --- ---------------------------------------
  NAME                           :   LATITUDE_MODEL

  ALIAS                          :   ('LAT', 'Used by the historical
                                     projects EARTH_PLANET')

  CLASS                          :   MODEL

  DEFINITION                     :   'Latitudes north of the equator shall
                                     be designated by the use of the plus
                                     (+) sign, while latitudes south of the
                                     equator shall be designated by the use
                                     of the minus sign (-). The equator
                                     shall be designated by the use of the
                                     plus sign (+).'

  SHORT_DEFINITION               :   'Latitude'

  UNITS                          :   Deg

  SPECIFIC_INSTANCE              :   (+00.000, 'Equator')

  DATA_TYPE                      :   REAL

  RANGE                          :   (-90.00, +90.00)
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   LONGITUDE_MODEL

  ALIAS                          :   ('LON', 'Used by the historical
                                     projects EARTH_PLANET')

  CLASS                          :   MODEL

  DEFINITION                     :   'Longitudes east of Greenwich shall be
                                     designated by the use of the plus sign
                                     (+), while longitudes west of Greenwich
                                     shall be designated by the use of the
                                     minus sign (-). The Prime Meridian
                                     shall be designated by the use of the
                                     plus sign (+). The 180^th^ meridian
                                     shall be designated by the use of the
                                     minus sign (-).'

  SHORT_DEFINITION               :   'Longitude'

  UNITS                          :   Deg

  SPECIFIC_INSTANCE              :   (-180.000, 'The 180^th^ Meridian')

  DATA_TYPE                      :   REAL

  RANGE                          :   (-180.00, +180.00)
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   PRODUCT_ID_MODEL

  ALIAS                          :   ('PRODUCT_NAME', 'Used by the
                                     historical projects EARTH_PLANET to
                                     identify their data products')

  CLASS                          :   MODEL

  DEFINITION                     :   'The PRODUCT_ID represents a permanent,
                                     unique identifier assigned to a data
                                     product by its producer'.

  SHORT_DEFINITION               :   'Product Identification'

  DATA_TYPE                      :   TEXT

  TEXT_SIZE                      :   40
  ------------------------------ --- ---------------------------------------

######## DATA ENTITY DICTIONARY ASSOCIATED WITH PRODUCT_X {#data-entity-dictionary-associated-with-product_x .Annex-2}

The models of LATITUDE_MODEL, LONGITUDE_MODEL and PRODUCT_ID_MODEL match
the data entities appearing within the data product PRODUCT_X and
therefore they are referenced within the current data entity dictionary.

**a) Data Entity Dictionary attributes**

  ------------------------------ --- ---------------------------------------
  DICTIONARY_NAME                :   PRODUCT_X \_Dictionary

  DICTIONARY_DEFINITION          :   'This dictionary contains the data
                                     entity definitions relative to the data
                                     product PRODUCT_X.'

  EXTERNAL\_                     :   (Planetary_Science_Data_Dictionary)
  DICTIONARY_REFERENCE               

  TEXT_FIELD_CHARACTER_SET       :   'ISO-LATIN ALPHABET No1'

  CASE_SENSITIVITY               :   NOT_CASE_SENSITIVE

  LANGUAGE                       :   ('English', en)

  DICTIONARY_VERSION             :   '1.a'

  DEDSL_VERSION                  :   'CCSDS 647.2-B-1.0'
  ------------------------------ --- ---------------------------------------

**b) Data Entities**

  ------------------------------ --- ---------------------------------------
  NAME                           :   HEADER

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents the header of the data
                                     product PRODUCT_X. It identifies an
                                     aggregation of values which are
                                     associated with an image array.'

  SHORT_DEFINITION               :   'Image Header Values'

  COMPONENT                      :   PRODUCT_ID_X(1 .. 1)

  COMPONENT                      :   ACQ_STATION(1 .. 1)

  COMPONENT                      :   ACQ_TIME(1 .. 1)

  COMPONENT                      :   CENTRE_COORD(1 .. 1)

  DATA_TYPE                      :   COMPOSITE
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   PRODUCT_ID

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents a permanent, unique
                                     identifier assigned to the data product
                                     PRODUCT_X.'

  SHORT_DEFINITION               :   'Product Identification'

  INHERITS_FROM                  :   PRODUCT_ID_MODEL
  ------------------------------ --- ---------------------------------------

+-----------------------------+---+--------------------------------------+
| NAME                        | : | ACQ_STATION                          |
+-----------------------------+---+--------------------------------------+
| ALIAS                       | : | ('ACQUSTAT', 'used in the FITS       |
|                             |   | header')                             |
+-----------------------------+---+--------------------------------------+
| CLASS                       | : | DATA_FIELD                           |
+-----------------------------+---+--------------------------------------+
| DEFINITION                  | : | 'It includes the identifier of the   |
|                             |   | station which has acquired the       |
|                             |   | data'.                               |
+-----------------------------+---+--------------------------------------+
| SHORT_DEFINITION            | : | 'Identifier of the acquisition       |
|                             |   | station'                             |
+-----------------------------+---+--------------------------------------+
| DATA_TYPE                   | : | Enumerated                           |
+-----------------------------+---+--------------------------------------+
| ENUMERATION_VALUES          | : | (AMERICA, EUROPE, ASIA)              |
+-----------------------------+---+--------------------------------------+
| ENUMERATION_MEANING         | : | ((AMERICA,'station located in        |
|                             |   | America'),                           |
|                             |   |                                      |
|                             |   | (EUROPE , 'station located in        |
|                             |   | Europe'),                            |
|                             |   |                                      |
|                             |   | (ASIA , 'station located in Asia'))  |
+-----------------------------+---+--------------------------------------+

  ------------------------------ --- ---------------------------------------
  NAME                           :   ACQ_TIME

  ALIAS                          :   ('ACQUTIME', 'Used in the FITS header')

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents the date and time of the
                                     acquisition of the data. Its format is
                                     the following one:
                                     YYYY-MM-DDThh:mm:ss.d\_\>Z. It conforms
                                     to the CCSDS ISO rules for date/time
                                     definitions. The acquisition time
                                     should correspond to the first scan
                                     line of the data.'

  SHORT_DEFINITION               :   'Date/Time of the data acquisition'

  DATA_TYPE                      :   Text

  TEXT_SIZE                      :   40
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   CENTRE_COORD

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents a coordinate centre'.

  SHORT_DEFINITION               :   'Centre coordinates'

  COMPONENT                      :   LATITUDE (1 .. 1)

  COMPONENT                      :   LONGITUDE (1 .. 1)

  KEYWORDS                       :   'LATITUDE BY LONGITUDE COORDINATE
                                     CENTRE'

  DATA_TYPE                      :   COMPOSITE
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   LATITUDE

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents the latitude used for
                                     the center coordinate'.

  INHERITS_FROM                  :   LATITUDE_MODEL
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   LONGITUDE

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents the longitude used for
                                     the centre coordinate'.

  INHERITS_FROM                  :   LONGITUDE_MODEL
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   W_IMAGE_SIZE

  CLASS                          :   CONSTANT

  DEFINITION                     :   'It represents the number of pixels for
                                     an image taken from spacecraft W'.

  SHORT_DEFINITION               :   'Spacecraft W Image pixel'

  RELATION                       :   ('size of', DATA_1)

  DATA_TYPE                      :   INTEGER

  CONSTANT_VALUE                 :   1 440 000
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   DATA_1

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents an image taken from
                                     spacecraft W'.

  SHORT_DEFINITION               :   'Spacecraft W Image'

  COMMENT                        :   'The image is an array of W_IMAGE_SIZE
                                     items called DATA_1_PIXEL'

  COMPONENT                      :   DATA_1_PIXEL (1 .. W_IMAGE_SIZE)

  KEYWORD                        :   'IMAGE'

  DATA_TYPE                      :   COMPOSITE
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   DATA_1_PIXEL

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents a pixel belonging to the
                                     image taken from spacecraft W'.

  SHORT_DEFINITION               :   'Spacecraft W Image pixel'

  DATA_TYPE                      :   INTEGER

  RANGE                          :   (0 , 255)
  ------------------------------ --- ---------------------------------------

########  DATA ENTITY DICTIONARY ASSOCIATED WITH PRODUCT_Y {#data-entity-dictionary-associated-with-product_y .Annex-2}

The models of LATITUDE_MODEL, LONGITUDE_MODEL and PRODUCT_ID_MODEL match
the data entities appearing within the data product PRODUCT_Y and,
therefore, they are referenced within the current data entity
dictionary.

**a) Data Entity Dictionary attributes**

  ------------------------------ --- ---------------------------------------
  DICTIONARY_NAME                :   PRODUCT_Y \_Dictionary

  DICTIONARY_DEFINITION          :   'This dictionary contains the data
                                     entity definitions relative to the data
                                     product PRODUCT_Y'.

  EXTERNAL\_                     :   (Planetary_Science_Data_Dictionary)
  DICTIONARY_REFERENCE               

  TEXT_FIELD_CHARACTER_SET       :   'ISO-LATIN ALPHABET No1'

  CASE_SENSITIVITY               :   NOT_CASE_SENSITIVE

  LANGUAGE                       :   ('English', en)

  DICTIONARY_VERSION             :   '1.a'

  DEDSL_VERSION                  :   'CCSDS 647.2-B-1.0'
  ------------------------------ --- ---------------------------------------

**b) Data Entities**

  ------------------------------ --- ---------------------------------------
  NAME                           :   PRODUCT_ID

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents a permanent, unique
                                     identifier assigned to the data product
                                     PRODUCT_Y'.

  SHORT_DEFINITION               :   'Product Identification'

  INHERITS_FROM                  :   PRODUCT_ID_MODEL
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   LATITUDE

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents the latitude used for
                                     the centre coordinate'.

  INHERITS_FROM                  :   LATITUDE_MODEL
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   LONGITUDE

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents the longitude used for
                                     the centre coordinate'.

  INHERITS_FROM                  :   LONGITUDE_MODEL
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   W_IMAGE_SIZE

  CLASS                          :   CONSTANT

  DEFINITION                     :   'It represents the number of pixels for
                                     an image taken from spacecraft W2'.

  SHORT_DEFINITION               :   'Spacecraft W2 Image pixel'

  RELATION                       :   ('size of', DATA_2)

  DATA_TYPE                      :   INTEGER

  CONSTANT_VALUE                 :   1 440 000
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   DATA_2

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents an image taken from
                                     spacecraft W2'.

  SHORT_DEFINITION               :   'Spacecraft W2 Image'

  COMMENT                        :   'The image is an array of W_IMAGE_SIZE
                                     items called DATA_2_PIXEL'

  COMPONENT                      :   DATA_2_PIXEL (1 .. W_IMAGE_SIZE)

  KEYWORD                        :   'IMAGE'

  DATA_TYPE                      :   COMPOSITE
  ------------------------------ --- ---------------------------------------

  ------------------------------ --- ---------------------------------------
  NAME                           :   DATA_2_PIXEL

  CLASS                          :   DATA_FIELD

  DEFINITION                     :   'It represents a pixel belonging to the
                                     image taken from spacecraft W2'.

  SHORT_DEFINITION               :   'Spacecraft W2 Image pixel'

  DATA_TYPE                      :   INTEGER

  RANGE                          :   (0 , 255)
  ------------------------------ --- ---------------------------------------

######## Number range ExampleNumber range FigureNumber range TableNumber range Annex_Level_1  MAPPING OF THE CONCEPTS BETWEEN THIS RECOMMENDATION AND THE ISO/IEC 11179-3:1994 STANDARD

(This annex **is not** part of the Recommendation)

**1) Mapping between the descriptors**

  ----------------------------------------- -----------------------------
  **DEDSL**                                 **ISO 11179-3:1994**

  Attribute_name                            Name

  Attribute_definition                      Definition

  Attribute_obligation                      

  Attribute_maximum_occurrence              Maximum occurrence

  Attribute_condition                       Condition

  Attribute_value_type                      Data type

                                            Maximum size

                                            Character set

                                            Language

  Attribute_comment                         Comment

  Attribute_value_example                   

  Attribute_default_value                   

  Attribute_inheritance                     

  Attribute_enumeration_values              

  Attribute_maximum_size                    

  Attribute_scope                           
  ----------------------------------------- -----------------------------

**2) Mapping between the attributes**

  ------------------------------ ----------------------------------------
  **DEDSL**                      **ISO 11179-3:1994**

  Name                           Name

                                 Identifier

                                 Version

                                 Registration Authority

  Alias                          Synonymous name

  Alias                          Context

  Class                          

  Definition                     Definition

  Short_definition               

  Comment                        Comments

                                 Classification scheme---Class name

  Units                          

  Specific_instance              

  Inherits_from                  

  Component                      

  Keyword                        Keyword

  Relation                       Related data reference

  Relation                       Type of relationship

                                 Representation class

  Language                       Form of representation
  ------------------------------ ----------------------------------------

  ------------------------------- ----------------------------------------
  **DEDSL**                       **ISO 11179-3:1994**

  Case_sensitivity                Form of representation

  Data_type                       Data type of data element values

                                  Maximum size of data element values

                                  Minimum size of data element values

                                  Layout of representation

  Data_type                       Code set

  Enumeration_values              

  Enumeration_meaning             

  Enumeration_convention          

  Range                           

  Text_size                       

  Constant_value                  

                                  Responsible organisation

                                  Registration status

                                  Submitting organisation

  Dictionary_name                 

  Dictionary_definition           

  External_dictionary_reference   

  Text_field_character_set        

  Dictionary_version              

  Dictionary_identifier           

  Dedsl_version                   
  ------------------------------- ----------------------------------------

######## Number range ExampleNumber range FigureNumber range TableNumber range Annex_Level_1  INFORMATIVE REFERENCES

(This annex **is not** part of the Recommendation)

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

\[C1\] *Procedures Manual for the Consultative Committee for Space Data
Systems*. CCSDS A00.0-Y-7. Yellow Book. Issue 7. Washington, D.C.:
CCSDS, November 1996.

\[C2\] *The Data Description Language EAST---Specification (CCSD0010).*
Recommendation for Space Data System Standards, CCSDS 644.0-B-1. Blue
Book. Issue 1. Washington, D.C.: CCSDS, May 1997. (FDIS 15889)

\[C-3\] *The Data Description Language EAST---A Tutorial.* Report
Concerning Space Data System Standards, CCSDS 645.0-G-1. Green Book.
Issue 1. Washington, D.C.: CCSDS, May 1997.

\[C-4\] *Standard Formatted Data Units---A Tutorial*. Report Concerning
Space Data System Standards, CCSDS 621.0-G-1. Green Book. Issue 1.
Washington, D.C.: CCSDS, May 1992.

\[C-5\] *Standard Formatted Data Units---Control Authority Procedures
Tutorial.* Report Concerning Space Data System Standards, CCSDS
631.0-G-2. Green Book. Issue 2. Washington, D.C.: CCSDS, November 1994.

\[C-6\] *Hierarchical Data Format (HDF).* Version 4.0r. National Centre
for Supercomputing Applications (NCSA).

\[C-7\] *Common Data Format (CDF).* Version 2.5.19a. National Space
Science Data Center, May 17, 1996.

\[C-8\] *Time Code Formats.* Recommendation for Space Data System
Standards, CCSDS 301.0-B-2. Blue Book. Issue 2. CCSDS April 1990. (ISO
11104)

\[C-9\] *UNIDATA Units Package.* NCAR, Version 1.11.5, August 18,
1997*.*

\[C-10\] *Information Processing---Representation of SI and other units
in systems with* *limited character sets.* ISO 2955-1983. Geneva:
ISO,1983*.*

\[C-11\] *Information Technology---Specification and standardisation of
data elements---part 3: Basic attributes of data elements*. ISO/IEC
11179-3:1994. Geneva: ISO, 1994.