Requirements

This clause defines a standard-based mechanism to interchange the DMF Metadata Elements defined in clause 5. This mechanism is based on:

·         a mapping between the DMF metadata elements and the geographic information metadata concepts defined by ISO standards.

·         a standard rule-based XML Schema Implementation of the geographic information metadata concepts defined by ISO standards.

The ISO standards specifying the geographic information metadata concepts and their XML Schema implementation are evolving. A first generation of standards is currently in use (ISO 19115, ISO 19115-2, ISO 19119, ISO/TS 19139 and ISO/TS 19139-2) while a new generation of standards is emerging (revision of ISO 19115 / ISO 19157 and their standardised implementations).

 

As a consequence, the standard based mechanism to interchange DMF Metadata is replicated for both generations. Clause 6.2 presents the mapping and implementation according to the first generation of ISO standards, whereas Clause 6.3 deals with the new generation of ISO standards.

Req 1.    A candidate DMF Metadata Set shall be composed of a set of well-formed XML Documents valid with respect to XML Schemas conformant to the standard encoding of the geographic information concepts defined by ISO (ISO/TS 19139 for the first generation of standards). These XML Documents shall also conform to one of the mappings between the DMF Metadata elements and the geographic information standards defined in clauses 6.2 and 6.3.

Req 2.    A candidate Metadata Catalogue shall be able to input and/or output compliant DMF metadata sets.

The composition of a metadata set is directly dependent on the implemented metadata classes. The packaging of the metadata classes takes into account the modular definition of the geographic information metadata concepts in ISO standards. The mappings documented hereafter document the interchange of the full set of metadata elements (all metadata classes), but the application of these mappings to the DMF metadata elements involves only the geographic metadata standards listed in Clause 2 for each metadata class.

The interchange of the DMF Metadata Elements is also based on registers of metadata items, especially regarding codelists.

The implementation of the DMF Metadata elements implied specific constraints on the instantiation of the geographic information concepts. These specific constraints apply to the geographic information metadata concepts for the two generations of standards. They are documented as a numbered list of textual constraints.

Req 3.    In order to meet the requirements expressed by a DMF Metadata Set, the XML Documents implementing a DMF metadata set shall meet the applicable DMF Specific Constraints.