"has" elements: DITA TC is considering removing them from DITA 2.0

[Kristen James Eberlein <kris@eberleinconsulting.com>]

These elements are part of the subjectScheme specialization, which was 
introduced in DITA 1.2. They were intended to support ontologies, but 
were poorly defined (the DITA TC member who championed them left IBM and 
TC before DITA 1.2 was released), and are (we think) in little or no use.

For more information, look at <hasInstance>, <hasKind>, <hasNarrower>, 
<hasPart>, <hasRelated>, and <relatedSubjects> in the DITA 1,3 spec:
http://docs.oasis-open.org/dita/dita/v1.3/errata02/os/complete/part3-all-inclusive/langRef/containers/subjectScheme.html

The DITA TC welcomes feedback, which we will consider before making the 
decision whether to remove these elements from the DITA 2.0 spec. If you 
are aware of an implementation using these elements, please let us know.

Anything removed from DITA 2.0 will be placed in an OASIS Open GitHub 
repository and upgraded to be compliant with DITA 2.0, to make it easy 
as possible for implementations to re-introduce specializations. The 
"has" elements would be simple to implement as a domain and add back 
into a document-type shell for subjectScheme.

--
Best,
Kris

Kristen James Eberlein
Chair, OASIS DITA Technical Committee