The Defence Geospatial Information
Working Group (DGIWG) Feature and Attribute Data (FAD)
Registry contains registers of geographic information concepts
used to characterize aspects of real world phenomena for different
information communities. In particular, geographic features
are real world phenomena associated with a location relative
to the surface of the earth, about which data are collected,
maintained, and disseminated.
Each register establishes a Feature Data Dictionary (FDD)
specifying independent sets of features and attributes that
may be used to describe geographic information - establishing
the universe of all feature concepts and attribute concepts
(including datatype listed value concepts) that may
be used in a particular context.
The DGIWG Feature and Attribute Data Registry makes use of
a common structure and coding scheme across its component
registers that conforms to ISO
19135, ISO 19126,
and aspects of ISO 19110.
This provides for flexible management of feature concept collections
and is used as a basis for harmonization and the establishment
of interoperability between different geographic information
The DGIWG controls and maintains multiple component Feature Data
Dictionary registers: the DGIWG FDD
and a set of National Extension FDDs. The FAD Registry includes additional
registers containing content drawn from specifications controlled and
maintained by other organizations.
The DGIWG FDD
incorporates many geographic information concepts from its predecessor, the DIGEST
Feature and Attribute Coding Catalogue
(FACC). Although DIGEST remains a valid standard,
part 4 (FACC)
has been sunsetted by DGIWG. Sunset standards are those that have been identified
and approved for retirement. Usually a pre-defined event and date are associated with the
eventual retirement of the standard. In addition, a replacement standard is frequently identified.
For FACC the DFDD is the replacement standard.