[sc34wg3] CTM: Proposal for relaxing the restriction on start-character for topic-ID in CTM

[Lars Heuer]

Hi Are,

> We are currently using the DNS-name as the topic identifier of a
[...]

> 3d-prod01.uio.no is a valid DNS-name, but is not a valid Topic ID in  
> LTM or CTM.
> Ref: http://www.isotopicmaps.org/ctm/ctm.html#sec-topic-identity

In CTM (I believe contrary to LTM), you can always use the following
syntax to allow topic identifiers that are used as keywords / would be
illegal as topic identifiers:

^<#topic-id-here> .

In your example you could write:

   ^<#3d-prod01.uio.no> - "3d-prod01.uio.no"; isa unix-server .

The ^ indicates that the following IRI reference should be interpreted
as item identifier. See also
<http://www.isotopicmaps.org/ctm/ctm.html#item-identifier>

But I wonder if using item identifiers makes sense in your use case.
Wouldn't it be much better to use a subject identifiers? Remember that
the topic identifiers are always resolved against the document IRI.

> - Are there any good reasons that a CTM-ID could not start with a
> number?

Yes, the ID production has the same constraints as the XML identifier
production. And if we'd allow the identifiers to start with a number,
how do we avoid that you'll use 42 as topic identifier? And how do we
distinguish your topic id "42" from the integer "42"?

Best regards,
Lars
-- 
Semagia 
<http://www.semagia.com>