[sc34wg3] Questions on

Murray Altheim sc34wg3@isotopicmaps.org
Tue, 12 Aug 2003 16:10:46 +0100

Re: The XML Topic Maps (XTM) Syntax [N0398]

 > F Differences with XTM 1.0 (Non-Normative)
 > This section lists the differences between XTM 1.1 and XTM 1.0.
 > The differences are:
 > =B7 The instanceOf element is now allowed inside the baseName element.=

In the XTM spec we provided a short description of what each subelement
means in context. What does <instanceOf> within <baseName> mean exactly?
Is this going to be spelled out somewhere by in an SC34/WG3 document?

 > =B7 The resourceRef element is now allowed inside the parameters,
 > instanceOf, and roleSpec elements.

Likewise, what does this mean? I think I can guess the first one, but
this has me a bit stumped. Given our recent discussions on topicmapmail,
its surprising to see the further expansion of <resourceRef>, though if
I'm not mistaken about the intent, maybe people do want to talk about
specific XML elements. XTM could be used, e.g., to map an SVG document.
XTM applications should not be limited by an inability to reify a
particular subject.

 > Ed. Note:
 > Complete list.

Nice to see only two fairly minor changes.

I also note on

 > Issue (xtm-href-whitespace):
 > Is whitespace allowed in the xlink:href attribute? If it is allowed,
 > how is it interpreted? If it is not allowed, what action is taken
 > when it is found?

that the answers given seem a bit confused, as there are two operating

   Q1: Is whitespace allowed in the xlink:href attribute?
   Q2: Is whitespace allowed within a URI?


   A1: The XML rules for attribute value normalization [XML] apply.
       If the whitespace is at the beginning or end of the attribute
       value and not in the URI itself, there might be an issue here.
       But given that the xlink:href attribute is declared CDATA, we
       don't allow leading or trailing space characters. IMO, there
       is no reason to make any statement about this in XTM, as it is
       handled by [XML].

         "If the attribute type is not CDATA, then the XML processor must=

          further process the normalized attribute value by discarding an=
          leading and trailing space (#x20) characters, and by replacing
          sequences of space (#x20) characters by a single space (#x20)

       But that's not us. We're CDATA.

   A2: RFC 2396 [URI] makes it clear that whitespace is not allowed
       within a URI and must be escaped. Therefore, any xlink:href
       attribute values containing whitespace are by definition not
       conformant with the definition of URI. They are not URIs. I
       think this is an application-specific issue, but certainly
       validators that know an attribute value is incorrect should
       pass that info on to the application. Whether we say anything
       about it I dunno.

BTW, the links in the TOC don't seem to work. Is that just me?



[N0398] http://www.y12.doe.gov/sgml/sc34/document/0398.htm
[XML] http://www.w3.org/TR/REC-xml#AVNormalize
[URI] http://www.ietf.org/rfc/rfc2396.txt
Murray Altheim                         http://kmi.open.ac.uk/people/murra=
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK                   =

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