[topicmapmail] Subject Identifiers metadata

[Thomas B. Passin]

Dan Corwin wrote:

>  > ... The type of the [reified] topic specifies that it is intended to
>  > represent a subject identifier, the value of the subject identifier
>  > could become the subject indicator or be captured with an occurrence
> 
> After re-reading this plan, I finally got it.  Sounds just right to
> me, and elegantly answers Kal's original question on this thread.
> 
> To reify any subject indicator, you just *declare* its new topic to
> have the "subjectIndicator" type, and nobody gets confused.  Bravo!
> 

Bingo!

> It also easily generalizes to allow *topic reification* in the same
> easy way: just declare the *type* of the new topic to be "Topic", and
> use the correct PSI, and there cannot be much confusion about what it
> represents, even in XTM 1.0 file format.
> 

Double Bingo!

> Which means it takes no new XTM syntax to implement this plan, just a
> couple of new or modified PSIs citing "best practice" documentation
> about the need to declare types carefully when doing reification.
> 

Exactly.

> Internally, would either of your TM engines need to do anything at all
> in a different way if this plan were adopted?

My engine would be ignorant of any special treatment due to a topic with 
such a PSI, just as it would be ignorant of any special processing due 
to a PSI representing geographic coordinates.  I would have to write an 
application or a utility library to take advantage of it, and if I found 
  a need to use this new concept and processing frequently, I would 
probably extend my engine.

Hmm, this suggests that it would be useful to be able to query an engine 
to discover what PSIs it understands natively.  Well, maybe for TMAPI 
1.1 ...

Cheers,

Tom P