Re: Question about all, choice, and sequence

"Weber, Heiko" <Heiko.Weber@softwareag.com> writes:

> I have a question about the "all"-, "choice"-, and "sequence"-sequences.
> What are the constraints on Schema definitions of these model groups?
> A choice which consists only of one element isn't really a choice but
> rather one required element, so is a choice with only one element allowed?
> Where do I find the constraints on model groups in the Schema spec? The
> section 3.7 "Model Group Definitions" didn't make it clear to me.

There are constraints on <all>, motivated by implementation concerns.
There are no constraints on <choice> or <sequence>, because type
derivation may need to do things like produce a single-element choice
in some circumstance.  Even empty groups are allowed.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
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