xml-dev - RE: Proposal Announcement - XML DTDs to XML docs

["Simon St.Laurent" <SimonStL@classic.msn.com>]

>What about issues such as redefining a parameter entity in the external 
subset? Or
>multiple identically named parameter entities within the DTD?

These could both be defined by specifying the behavior for the 
DTD-as-document, just as they are now for DTDs.  I see no difficulty here.

>Sticking with
>parameter entities, what if the same entities behaved as a content model and 
an
>attribute name? How and why would you make the distinction with the proposed
>syntax?

How and why would you make the distinction with the current syntax?  Why would 
this be so difficult to do in a document rather than the current syntax?  Are 
you saying that it would be crossing element boundaries and therefore break 
the well-formedness requirements?  The syntax is currently (obviously) 
incomplete; I'll see what I can do to address this issue.  I've obviously done 
an inadequate job here.

Parameter entities are admittedly my least favorite part of XML, a necessary 
evil and a powerful tool.  There may well be limits on how well they can map 
to this model - but is that a significantly worse limitation than the 
abolition of the & content model?  I think the manageability you'd gain with 
this representation of XML DTDs would more than compensate for any loss 
incurred by the enforced simplification of parameter entities.

>I think that the syntax that describes the structure of documents can validly 
be
>different from the syntax that frames data because they're trying to 
accomplish
>very different things.

To a certain extent, this is certainly true.  However, I think there's a 
strong case to be made for using a single syntax - see the advantages listed 
in the Rationale.  I'm very happy with the document syntax XML inherited from 
SGML, particularly as XML made that syntax much more strictly enforced.  I'm 
not as happy with the DTD syntax - and this seems like a good way to take 
advantage of the power of XML's document syntax.  The current DTD syntax is 
workable - but not very extensible.  

I see a lot of effort being put into schemas and other projects that seem to 
add additional layers of complexity, and require applications to implement all 
kinds of extra linkages.  By standardizing the linkage mechanism and the 
format for these extensions (as XLink or a derivative and XML documents, 
respectively), I hope to see a lot less EBNF and a lot more XML.

Simon St.Laurent
Dynamic HTML: A Primer / XML: A Primer / Cookies


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