[sc34wg3] Questions on N0396: (15) [value] vs [resource] property on occurrence

Lars Marius Garshol sc34wg3@isotopicmaps.org
23 Apr 2003 01:52:07 +0200

* Jan Algermissen
| Occurrences relate information resources to subjects. These
| information resources can have addresses. If the same information
| resource is 'used' more than once in a topic map I'd like to be able
| to provide the user with that information. If I throw the locator of
| <resourceData> resources away, I loose that ability in some
| cases. Since it does not hurt to keep the locator, why takle power
| away from topic maps. What is the purpose?

I think you should distinguish between creating a topic that

 a) the <resourceData> element,

 b) the string that is the resource, and

 c) the topic-string relationship.

If you want to create a topic that represents the <resourceData>
element (a) you have no choice: create a topic whose subject address
refers to the element in the file where you want to point to it.

If you want to reify the topic-string relationship (c) you just do
straightforward reification of the occurrence.

How to achieve (b) is currently an open issue:
  <URL: http://www.ontopia.net/omnigator/models/topic_complete.jsp?tm=tm-standards.xtm&id=strings-as-subjects >

The resolution Graham and I are proposing to this is here:
  <URL: http://www.y12.doe.gov/sgml/sc34/document/0397.htm >
(Sorry, whoever edited this with MS W*rd broke the anchors. :-| )

Input on this is very much welcome. (That's why we created an issue
for this. :)

| Well, if there is no locator, fine with me. I just don't want to
| throw information away.

If you look at the XTM spec you'll see that information *is* being
lost. The whole point of having a model is to lose the information you
don't want, though. Otherwise we could just point to XTM 1.0 and say
"there's the model". So whether you wrote the 'a' in Jan as &#65; or
as 'a' you can't find out after the TM has been deserialized.

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