[topicmapmail] Questions About XTM Occurrence Semantics

[Lars Marius Garshol]

Hi Peter,

* Peter P. Jones
>
> Imagine I have a topic for some subject and in some scope, say  
> {a,b,c},
> that topic has an occurrence with a particular locator.
>
> If I reify that occurrence, what is the precise meaning of the  
> reifying
> topic construct?
>
> Is it:
> a) A reification of the particular information item that is that
> occurrence? So I can talk about the information item.
> b) A reification of the particular occurrence of the subject somewhere
> (outside TM-land)?
> c) Something else I haven't thought of.

The answer is b). XTM 1.0 is silent on this (as far as I can  
remember), but TMDM is (IMHO) pretty clear on this:

   http://www.isotopicmaps.org/sam/sam-model/#d0e994

> What I would like is to reify a particular occurrence, but I would  
> also
> like the intent of the reification to be that I am reifying the
> occurrence of the subject and not the technical construct of the TM
> information item, if that is possible.

That's the standard semantics, so no worries.

> In the reifying topic construct, does it make a difference w.r.t. the
> above whether I use a subject locator or subject identifier.
> I.e. does subject locator provide for (b) while subject identifier
> provides for (a)?
> Or are matters more like (c)?

If you use a subject locator in the syntax the standard says nothing  
about what it might mean beyond the general semantics of the subject  
locator constructor. I would take that to mean that using a subject  
locator means you are talking about the XML element in the XTM file.

I hope this helps.

-- 
Lars Marius Garshol                         Mobile: +47 98 21 55 50
CTO, Ontopia                                Office: +47 23 23 30 83