A representation term is a word, or a combination of words, that semantically represent the data type (value domain) of a data element. A representation term is commonly referred to as a ''class word'' by those familiar with data dictionaries. ISO/IEC 11179-5:2005 defines ''representation term'' as a ''designation of an instance of a representation class'' As used in

ISO/IEC 11179 The ISO/IEC 11179 Metadata Registry (MDR) standard is an international ISO/IEC standard for representing metadata for an organization in a metadata registry. It documents the standardization and registration of metadata to make data understandab ...

, the representation term is that part of a data element name that provides a semantic pointer to the underlying data type. A ''

Representation class A representation term is a word, or a combination of words, used as part of a data element name. ''Representation class'' is sometimes used as a synonym for representation term. In ISO/IEC 11179, a ''representation class'' provides a way to clas ...

'' is a class of representations. This ''representation class'' provides a way to classify or group

data element In metadata, the term data element is an atomic unit of data that has precise meaning or precise semantics. A data element has: # An identification such as a data element name # A clear data element definition # One or more representation terms ...

s. A ''Representation Term'' may be thought of as an attribute of a

in a

metadata registry A metadata registry is a central location in an organization where metadata definitions are stored and maintained in a controlled method. A metadata repository is the database where metadata is stored. The registry also adds relationships with r ...

that classifies the data element according to the type of data stored in the data element. Representation terms are typically "approved" by the organization or standards body using them. For example, the UN publishes its approved list as part of the UN/CEFACT Core Components Technical Specification. The Universal Data Element Framework uses a subset of CCTS representation terms and assigns numeric codes to those used.

Use cases for representation term

Managing value domains

A value domain expresses the set of allowed values for a data element. The representation term (and typically the corresponding data type term) comprise a taxonomy for the value domains within a data set. This taxonomy is the representation class. Thus the representation term can be used to control proliferation of value domains by ensuring equivalent value domains use the same representation term.

Finding equivalent properties

When a person or software agent is analyzing two separate metadata registries to find property equivalence, the Representation Term can be used as a guide. For example, if system A has a Data Element such as PersonGenderCode and system B has a data element such as PersonSexCode the code suffix might assist the two systems to only match data elements that have the suffix "Code". However, a taxonomy of property terms (i.e. "Sex" or "Gender") is much more efficient in this respect.

Inference

The Representation Term can be used in many ways to do inferences on data sets. Representation Terms tells the observer of any data stream about the data types and gives an indication of how the Data Element can be used. This is critical when mapping metadata registries to external Data Elements. For example, if you are sent a record about a person you may look for any "ID" suffix to understand how the remote system may differentiate two distinct records.

Required fields

Representation Terms are also used to make inferences about the requirements of a property. For example, if a data stream had Data Element PersonBirthDateAndTime you would know that BOTH the date AND time are available and relevant, not just the date. If the birth time was optional, a separate data elements should be used such as PersonBirthDate and PersonBirthTime.

Finding data warehouse dimensions and measures

When creating a data warehouse, a business analyst looks at the Representation Terms to quickly find the dimensions and measures of a subject matter in order to build OLAP cubes. For example: # Indicator or Code are used to create data warehouse dimensions # Date or DateTime are used to relate to the time dimension, which are frequently shared between cubes using conformed dimensions # Amount, Number, Measure or Value terms (which can be added together) are candidates for a measurement # Name and Text are used for screen labels or other descriptive elements # Percent needs to be analyzed since they can't really be added together with clear meaning # ID is used to remove duplicate records

Core Components Technical Specification

The joint ISO/UN Core Components Technical Specification formally define both the allowed set of representation terms and the corresponding set of data types. ISO 15000-5 is an implementation layer of ISO 11179 and normatively expresses a set of rules to semantically define conceptual and physical/logical data models for a wide variety of uses. In ISO 15000-5, the representation term provides a mechanism to harmonize the value domains of candidate data elements before being added to the overall data model(s). ISO 15000-5 is being used by a number of government, standards development organizations, and private sector as the basis for data modeling.

Universal Data Element Framework

Some informal standards such as the Universal Data Element Framework (which refer to a Representation Term as a "Property Word") assign unique integer IDs to each Representation Term. This allows metadata mapping tools to map one set of data elements into other metadata vocabularies. An example of these mappings can be found at Property word ID. Note that as of November 2005 the UDEF concepts have not been widely adopted.

Example of representation terms as an XML suffix

For example, if an XML Data fragment had the following: 123-45-6789 John Smith 1990-08-14 In the example above, the Representation terms are "ID" for the , the suffix "Name" for the Given and Family names, and "Date" for the .

Sample representation terms

The following are samples of Representation Terms that have been used for the exchange of electronic messages in systems such as NIEM or

GJXDM The Global Justice XML Data Model (GJXDM or Global JXDM) is a data reference model for the exchange of information within the justice and public safety communities. The Global JXDM is a product of the Global Justice Information Sharing Initiative ...

3.0: ote: the restrictions expressed here are limited to those specifications and do not represent universal consensus

Pros of representation terms

* Use of representation terms in a data element name is a convention that is widely adopted by several large systems such as NIEM,

and

ebXML Electronic Business using eXtensible Markup Language, commonly known as e-business XML, or ebXML (pronounced ee-bee-ex-em-el, 'bi,eks,em'el as it is typically referred to, is a family of XML based standards sponsored by OASIS and UN/CEFACT whose m ...

. * Many data architects that are responsible for mapping XML from foreign sources find Representation terms very useful. * Standards such as the UDEF depend on accurate coding of Representation Terms. * Tools that validate against enumeration lists can distinguish coded values quickly by looking for the "Code" suffix. *

Dimensional analysis In engineering and science, dimensional analysis is the analysis of the relationships between different physical quantities by identifying their base quantities (such as length, mass, time, and electric current) and units of measure (such as mi ...

of data can use representation terms for creating data warehouses. Representation terms such as Code and Indicator can be converted into dimensions and Amounts and Measures can be converted to measures in a fact table.

Cons of representation terms

* No universal agreement exists as to the definitive set of representation terms. * There is not always a direct relationship between a representation term and the value domain it represents. This is caused by further qualifying the corresponding data type term.

Standards that use representation terms

* Electronic Business using eXtensible Markup Language * The US Government's

National Information Exchange Model NIEM ( ) originated as an XML-based information exchange framework from the United States. NIEM also supports NIEM JSON exchanges. NIEM is currently developinthe NIEM Metamodel and Common Model Formatwhich can be expressed in any data serializatio ...

requires the use of representation terms for XML data elements. * The US Department of Justice data exchange standards Global Justice XML Data Model required the use of representation terms for XML data elements. oteThis is an extremely limited set of the wide range of standards that specify the use of representation terms.

Notes

ISO/IEC 11179-5 3.11
(238K zip file) # {{note, reptermasattrI
ISO/IEC 11179-3:2003 5.4
(546K zip file) it is actually ''

representation class A representation term is a word, or a combination of words, used as part of a data element name. ''Representation class'' is sometimes used as a synonym for representation term. In ISO/IEC 11179, a ''representation class'' provides a way to clas ...

'' which is specified as an attribute of a

External links

ISO/TS 15000-5:2005 Electronic Business Extensible Markup Language (ebXML) -- Part 5: ebXML Core Components Technical Specification, Version 2.01(ebCCTS)
(1MB pdf file)
ISO/IEC 11179-3:2003 Metadata registries (MDR) — Part 3: Registry metamodel & basic attributes
(546K zip file)
ISO/IEC 11179-5:2005 Metadata registries (MDR) — Part 5: Naming and identification principles
(238K zip file)
ISO/IEC TR 20943-1:2003(E) Procedures for Achieving Metadata Registry Content Consistency — Part 1: Data elements
See page 84.(700K zip file)
DOJ and GJXDM training slides on naming

ISO/IEC JTC 1/SC 32/WG 2 Metadata
* BROKEN LINK: http://ashcomp.com/DOI_Representation_terms.html US Department of Interior representation terms
NIEM training see slide on page 8 for terms covered in the training class.

ISO/IEC 11179 Metadata registry Metadata Semantics