[sc34wg3] XTM 2.0 topicRef - proposal for an erratum

[Lars Heuer]

Hi Steve,

[...]
> Please explain in what sense (or when) the option to reference a topic by
> subject locator or subject identifier is "missing". I don't see it.

Example:

CTM:

%prefix tech <http://psi.example.org/technology/>

tech:tmxml isa tech:syntax .



Convert this to XTM 2.0:

<topicMap xmlns="http://www.topicmaps.org/xtm/" version="2.0">
  <topic id="id454023">
    <subjectIdentifier href="http://psi.example.org/technology/tmxml"/>
    <instanceOf>
      <topicRef href="#id454132"/>
    </instanceOf>
  </topic>
  <topic id="id454132">
    <subjectIdentifier href="http://psi.example.org/technology/syntax"/>
  </topic>
</topicMap>


Result using XTM 2.1:

<topicMap xmlns="http://www.topicmaps.org/xtm/" version="2.1">
  <topic>
    <subjectIdentifier href="http://psi.example.org/technology/tmxml"/>
    <instanceOf>
      <subjectIdentifierRef href="http://psi.example.org/technology/syntax"/>
    </instanceOf>
  </topic>
</topicMap>


As you see, the XTM 2.0 syntax forces us to invent additional topic
ids (which are resolved as item identifiers) since we only have the
<topicRef/> available to model the type-instance relationship between
"TM/XML" and "syntax". XTM 2.1 avoids that: No additional topic
identifiers are required since we're able to reference the "syntax"
topic by its subject identifier.

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