Re: [xml-dev] DTD vs XSD: No Duplicate Types in (Mixed) ContentModels

[David Carlisle <davidc@nag.co.uk>]

On 31/01/2011 14:22, Maik Stührenberg wrote:

> But when in mixed content models duplicate types are not allowed -- why
> are they allowed in element content models? The additional #PCDATA of a
> mixed content model should have only little effect on the question of
> determinism, or do I forget anything (maybe the whitespace characters
> that are allowed...)?


If there is a #PCDATA token you can't use , or ? in dtd only 
(#PCDATA|a|b|c)* and the deterministic content model rule explictly only 
applies to element content.

http://www.w3.org/TR/xml/#sec-element-content



> But your declaration is (of course) accepted by the parser because it is
> non-ambiguous. However, the question remains: why is the original

the requirement to check that teh content model is deterministic os 
marked as "an error"
http://www.w3.org/TR/xml/#dt-compat
for compatibility (with SGML)

"an error" is not "fatal error" and so formally it means that the dtd is 
in error but a system isn't obliged to report that. It may make it an 
error, or may just give a warning, or may just work.

David

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