[topicmapmail] Subject Identifiers metadata

[Lars Marius Garshol]

* Kal Ahmed
| 
| The note says that you cannot reify a topic. You can, however reify
| any characteristic of the topic.

I guess I should step in here to clear this up, despite this post
being quite old by now. Topics and topic characteristics are actually
in the same boat as regards reification in TMDM, even though this may
not be immediately obvious.

The reason you can't reify a topic is that reification is done with
subject indicators, and this means that attempting to reify a topic
(that is, creating a topic B that represents topic A) is impossible
because you actually wind up creating a topic B representing topic A's
subject, which means that A and B have the same subject, and must
merge.

Now, if you think about it, it becomes clear that reifying an
association between A and C does not actually create a topic that
represents the *association*, but rather the real-world *relationship*
that the association represents. (In TMRM terms this would be the
subject of the A-node.)

So, in short, the TMDM lets you create topics for the things
represented by TMDM information items, but not for the items
themselves. (Well, it's slightly more complicated than this, actually.
You can create you own convention for this if you want, but there is
no standard mechanism for it.)

Any thoughts on whether the language in the TMDM should be modified to
make this clearer?

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