Again wit da AND and Repetitions

Terje Norderhaug terje at
Sat May 15 22:17:34 BST 1999

At 5:11 PM 5/14/99, roddey at wrote:
>>>Does anyone believe that these can be done in less than brute force tree
>>XML requires deterministic content models. This allows validators to do
>>their job without having to look more than one element ahead or do brute
>>force tree searches.
>Actually it does not require deterministic models, it just allows you to check
>for them. And, I guess its not really what XML does or does not do that's in
>question here, its what the new upcoming schema spec proposes to do that's at

The XML 1.0 specification, 3.2.1 states that:

"For compatability, it is an error if an element in the document can match
more than one occurance of an element type in the content model".

See also Appendix E to the specification, which describes in further detail
what is meant by a deterministic and ambigous content model.

It follows from the definition that a validating XML parser doesn't have to
look ahead. This is important as it simplifies implementing validation.

-- Terje <Terje at> | Media Design in*Progress

   Software for Mac Web Professionals at <>
   Take advantage of XML with Emile, the first XML editor for Mac.

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