xml-dev - Re: New schema spec

[Paul Prescod <paul@prescod.net>]

roddey@us.ibm.com wrote:
> 
> Well, its kind of a practical matter. From a support perspective (kind o'
> important to a company our size) proving that the content model is ambiguous
> means never have to say you're sorry, or at least have to say you're sorry less
> often. 

My question is: under what circumstances does an ambiguous content model
cause a problem?

<!ELEMENT ABC (DEF?,DEF)>

Okay, so this is ambiguous according to the XML/SGML definition of
ambiguous. What's the problem? It matches the same thing as DEF, DEF?

<!ELEMENT ABC (DEF|DEF)>

This is ambiguous according to the more widely accepted definition. I
still don't see a problem. It matches the same thing as DEF.

I think that your concern about ambiguity comes from a background in
context free grammars where it is a big problem. In XML, every element is
explicitly separated from every other one with tags so ambiguity is not a
problem.

-- 
 Paul Prescod  - ISOGEN Consulting Engineer speaking for only himself
 http://itrc.uwaterloo.ca/~papresco

Diplomatic term: "Emerging Markets"
Translation: Poor countries. The great euphemism of the Asian financial
             meltdown. Investors got much more excited when they thought 
they could invest in up-and-comers than when they heard they could invest 
in the Third World.(Brills Content, Apr. 1999)

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