[sc34wg3] SAM 3.4.4 Reification and 3.4.5 Properties

Lars Marius Garshol sc34wg3@isotopicmaps.org
15 Apr 2003 21:47:58 +0200

* Luis J. Martinez
| Are the properties [subject addresses] and [reified] representing
| the same thing when the subject is an information item in the topic
| map?

* Lars Marius Garshol
| Good question. The answer is 'no'.

If I think it's a good question I suppose I should also answer it.
Sorry about that; it slipped past unnoticed.

The [reified] item contains either null or a single topic map, topic
name, variant, occurrence, association, or association role item. If
it does not contain null the item it contains represents the subject
of the topic.

The [subject addresses] property, on the other hand, contains a set of
locator items. These locator items reference the information resource
which is the subject of the topic. 

What I suppose you are thinking of is one of the following two:

 a) the topic item reifies some part of the topic map. In this case,
    that part of the topic map will be in the [reified] property, and
    [subject addresses] should be empty (though it is not required to

 b) the [subject addresses] property contains a locator that matches
    one of the [source locators] of some other information item.

In case a) I think the explanation under that item covers what I want
to say. In case b) this simply means that the subject of the topic is
some information resource outside the topic map, perhaps an XML
element in an XTM document, but that doesn't really have anything to
do with the topic map, except that the topic map was loaded from it.

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