[sc34wg3] Towards TMDM 3.0

[Inge Henriksen]

An annoying "feature" on some topic map engines is that the item identifiers are discarded each time you do a export to XTM and then a import from XTM of the same map again. According to TMDM there is no problem with this, but when I made my own topic map engine (TM++) I made sure that the engine persist the item identifiers.

-Inge

-----Original Message-----
From: sc34wg3-bounces at isotopicmaps.org [mailto:sc34wg3-bounces at isotopicmaps.org] On Behalf Of Rani Pinchuk
Sent: 23. februar 2009 11:00
To: Discussion of ISO/IEC 13250 Topic Maps
Cc: Lars Marius Garshol
Subject: Re: [sc34wg3] Towards TMDM 3.0

Dear Lars,

Saying that Item identifiers (or subject identifiers, or subject 
locators) were never meant to be unique *across* topic maps does not 
solve the problem really.

Section 6.2 of TMDM explains that during the merging of two
topics A and B, a new topic C is created with its item identifiers 
property set to the union of the values of A and B's item identifiers 
properties.

Why do we do that? What is the use of collecting item identifiers from 
different topics (in possibly different topic maps) to the current one 
if they have no uniqueness outside of the topic map? How can we use 
those item identifiers?

Kind regards,

Rani

Lars Marius Garshol wrote:
  > I guess you are referring to section 4.2 of this paper? I'm afraid I
> don't see any problem in this section. Item identifiers (or subject  
> identifiers, or subject locators) were never meant to be unique  
> *across* topic maps, only *within* each topic map.
> 
> I think if you reflect on it for a moment, you will see that in fact  
> no other policy is possible. Even your proposed change (just one [item  
> identifier], new property [item origins]) doesn't solve this. It's  
> entirely possible to create two topics in different topic maps with  
> the same item identifier. For example, in different TM engines, or on  
> different machines.
> 
> In any case, there is no problem to be solved here. Different topics  
> in different topic maps can have the same subject identifier, which is  
> how we can have interoperability between topic maps. Item identifiers  
> are essentially the same.
> 
> --Lars M.
> http://www.garshol.priv.no/blog/
> http://www.garshol.priv.no/tmphoto/
> 
> 
> 
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> sc34wg3 mailing list
> sc34wg3 at isotopicmaps.org
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-- 
Rani Pinchuk
Project Manager
Space Applications Services
Leuvensesteenweg, 325
B-1932 Zaventem
Belgium

Tel.: + 32 2 721 54 84
Fax.: + 32 2 721 54 44

http://www.spaceapplications.com
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