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tm-pubsubj message

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Subject: Re: [tm-pubsubj] Re: [tm-pubsubj-comment] Comments on Use Case


After I sent out my previous message, I realized that I was quoting from 
XML Schema fro ISO 13250 Topic Maps, at

>"A subject descriptor is a reference to a positive, unambiguous, 
>indication of the identity of a subject.
>For example, it could be a reference to some descriptive text, a Dewey 
>Decimal Code or a Universal Decimal Classification. A public subject 
>descriptor is a subject descriptor which is designed to be used as a 
>common referent of the identity attribute in many topic maps."
>"Any two topics that have the same URI as the value of their identity 
>attribute  are considered to be equivalent to a single topic that is the 
>union of the  contents of the two topics, and of any associations that 
>reference them."

I found it very useful to look at the above definitions together with the 
definitions from ISO/IEC FCD 13250:1999 - Topic Maps  at 

subject descriptor
Information which is intended to provide a positive, unambiguous indication 
of the identity of a subject, and which is the referent of an identity 
attribute of a topic link.

NOTE 6: there is no requirement that a subject descriptor be text, although 
it can be the text of a definition of the subject. it can also, for example 
be a listing a  catalog of subjects, such as a acquisition number of an 
asset in a museum collection, a catalog number is a sales catalog, or a 
subject heading in a catalog of library subject headings. The distinction 
between a subject descriptor that happens to be a definition and an 
ordinary occurrence of a definition is that, in the case of the subject 
descriptor, the topic link's author has indicated (by referring to it by 
means of the value of the identity attribute) that it is to be regarded as 
the authoritative definition of the organizing principle of the topic link. 
In the other case, by characterizing a definition as a definitional 
occurrence, the author is merely acknowledging the existence of the 
definition and its possible relevance to the subject of the topic link.

NOTE 7: Subject descriptors may be offline resources.

public subject descriptor
A subject descriptor (see the definition of subject descriptor) which is 
used (or, especially, which is designed to be used) as a common referent of 
the identity attributes of many topic links in many topic maps. The subject 
described by the subject descriptor is thus easily recognized as the common 
binding point of all the topic links that reference it, so that they will 
be merged.

The optional subject identity (identity) attribute refers to one or more 
indications (subject descriptors) of the identity of the subject (the 
organizing principle) of the topic link. All of the other topic 
characteristics specified by the topic link are regarded as elaborating, 
and in no way contradicting, the subject described by the subject 
descriptor(s), if any. There are no restrictions on the kinds of 
information that may be referenced by an identity attribute.

NOTE 20: The information referenced by an identity attribute may or may not 
take the form of a topic link in a topic map document, may or may not be 
text, may or may not be machine-interpretable, and may or may not be online.

Any two or more topic links that reference the same subject by means of 
their identity attributes are equivalent to a single topic link that has 
the union of the characteristics (the names, occurrences, and associations) 
of both topic links. The two or more topic links may be merged, and/or 
applications may process and/or render them as if they have been merged.

NOTE 21: The two or more topic links do not have to refer to the same 
subject descriptor in order to be merged under this rule. It is only 
necessary that the subject that is somehow indicated by the two identity 
attributes be one and the same subject. If two or more topics refer to 
exactly the same subject descriptor, the subject descriptor may be 
described as a public subject descriptor, and it becomes possible to 
automate the merging of all such topics by making the assumption that, if 
they all share the same subject descriptor, they all share the same subject 

Similarly, if the identity attribute references one or more topic links, 
topic map processing applications must regard the referencing topic link, 
and all the referenced topic links, as having one and the same subject, and 
therefore they may all be merged.

And now compare this to the definitions in XTM at 
http://www.topicmaps.org/xtm/1.0/ . We have

subject identity
1. The <subjectIdentity> child of a <topic> element.
2. That which makes two subjects identical, or distinguishes one subject 
from another. The determination of subject identity is aided, and may be 
automated, by the use of published subjects.
3. A criterion for merging topics as defined in Annex F: XTM Processing 

subject indicator -  A resource that is intended by the topic map author to 
provide a positive, unambiguous indication of the identity of a subject.

published subject indicator - A subject indicator that is published and 
maintained at an advertised address for the purpose of facilitating topic 
map interchange and mergeability.

These definitions bring up many questions for me such as

What is the difference between a "resource" and "information"?

Information that is not maintained at an advertised address now will need 
to be if it is to become  a published subject. This would be a requirement 
for anyone who wanted their information included. We would in a sense be 
promoting the publication of information at a stable online address?

Some more food for thought.

Best regards,

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