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Re: [xml-dir] Re: [Simple] Presence Relax NG schemas
> I'll agree that it is not definitely an optimal solution to have two
> definitions. Anyway, as you know, with the current W3C schemas you
> cannot express where to put e.g. some extension elements when there are
> many possible extension points: you could add e.g. <dm:person> element
> under <presence>, <tuple> and <status>. And once you add new schemas
> extension points just increase. However, these Relax NG schemas do not
> allow this ambiguity. So they follow more strictly the intention of the
> specs. Of course if these schemas don't correctly follow the specs, I am
> glad to receive fixes.
> Secondly, I am aware that ietf/xml-dev had these schema tool discussions
> awhile back ago. AFAIK the recommendation does not mandate to use only
> W3C schemas, it just seems to be the prevailing habit. At least in this
> particular case Relax NG fits better for the task, imo.
Sure, working groups should always be able to discuss XML schema vs.
RELAX vs. DTD. However, that discussion is appropriate in the beginning
of the cycle. The group has already chosen XML schema, and I don't
believe you are proposing to change that decision. As such, I think its
far more important to have a single definition of the grammar.
I'm afraid I have to agree with Jonathan here. I don't especially care what
definition tool is used (although I like it when one is used...), but using
more than one could lead to all sorts of unnecessary excitement. I personally
haven't used Relax NG for much, but I use both DTDs and Schemata all the time
and the overlaps between the two can be... well, interesting.
I guess having more than one defintion is OK as long as only one of them is
considered to be normative.
There's some similarity between this issue and the issue of recasting existing
data formats in XML. It may make sense to define, say, an XML variant of the
iCalendar format, but unless a wholesale migration to the XML format is planned
the original format needs to be the normative one. Imposing additional
constraints, or worse, adding extensions in a secondary format is a really
bad idea IMO.
Ned
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