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Re: questions about element declarations




> From: Michael Sperberg-McQueen <U35395@UICVM.CC.UIC.EDU>

> 
> >>* Should XML allow nondeterministic content models (11.2.4.3)?
> >
> >Again, how much does this complicate validation? I'm not ambiguity
> >expert, but could the problem be solved simply by stipulating that a
> >token is always matched to the first place in the content model it
> >can match, without lookahead?
> 
> . . .
> 
> One could also argue against lifting this restriction on the ground that
> the restriction isn't hard to live with, and it's better to deviate from
> 8879 as little as possible.  That's a fair political argument, and one
> I'm amenable to. But evaluating it requires a dispassionate examination
> of the technical issues first.  This particular change does not, in any
> case, have any effect whatever on our ability to generate, for any given
> XML instance, a valid SGML prolog that will cause an SGML parser to
> produce the same ESIS as an XML parser, which is, I think, the level of
> compatibility that matters most.

Michael, I hear you saying that, given an XML document without its
declarations, there exists a set of SGML declarations that will allow
my SGML parser to generate the same ESIS as an XML parser.

However, if someone sends the XML declarations, I should no longer
be free to develop an arbitrary DTD with which to edit the document,
so if I am going to use an SGML editor to edit this XML document, I'll
need to convert the XML declarations into an equivalent set of valid
SGML declarations.

Therefore, my question/concern is:  if we allow in XML content models
that are not allowed in SGML and I receive an XML instance *with its
declarations*, is there a simple algorithm to convert the XML
declarations into SGML declarations so that I can process the document
with my SGML tools?