XML Schema catalog identifiers

Each Schema document must be uniquely identified using a Uniform Resource Name (URN). Each Schema document has a version-independent as well as a version-specific URN.

An XML resolver should be used to uniquely identify an XML Schema in order to map to a local resource. The DITA specification includes both URN- and URL-based versions of the XML schemas. The URL versions are included as a convenience for use with tools that do not support catalog based resolution and are not normative.

The catalog identifiers use the following patterns.

Creator	Pattern
OASIS DITA Technical Committee	`urn:oasis:names:tc:dita:xsd:filename.xsd:version`
Subcommittee of the OASIS DITA Technical Committee	`urn:oasis:names:tc:dita:spec:subcomittee-specialization:xsd:filename.xsd:version`

where:

subcomittee-specialization indicates the subcommittee and specialization, for example, "machinery" or "learning".
filename is the base name of the document-type shell or module component.
version either is a DITA version number (for example, 1.0, 1.1, 1.2, or 1.3) or is omitted entirely.

Note that "oasis" is the owner identifier; this indicates that the artifacts are owned by OASIS. The keyword "dita" is a convention that indicates that the artifact is DITA-related. The pattern "urn:oasis:names:tc:dita" is a convention that indicates that the artifact is DITA-related and defined by the OASIS DITA Technical Committee.