[topicmapmail] DM zero source locators

[Lars Marius Garshol]

* Peter P. Jones
|=20
| W.r.t. the DM, should an information item should ever be allowed to
| have zero source locators?

A similar issue was raised by Kal Ahmed at the meeting in Montr=E9al and
resolved there:
<URL: http://www.ontopia.net/omnigator/models/topic_complete.jsp?tm=3Dtm-st=
andards.xtm&id=3Dtopic-identity-required >

The rationale will appear in the meeting report, once it's published,
but requiring a value for one of the three [source locators], [subject
identifiers], [subject locator] properties means one can rely on the
topic to always have some defined identity.

We can't require a source locator, however, since it's entirely
possible to write XTM topic maps where topics are created which have
no source locator, and allowing this has been the practice ever since
XTM came out.

--=20
Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >