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The elements in the group "all" may appear once or not at all.
In this case I think appropriate solution is to use "choice" group element.
> "Nada Reinprecht" <Nada_Reinprecht@nemmco.com.au> writes:
>
> > The problem is:
> > there are a, b, c and d entities that can be represented with the same type
> > x
> > there is e entity that can be represented with type y which is derivation
> > of type x.
> > there is need to identify a, b, c, d and distinguish between them
> > all these entities are used in the same transaction where any combination
> > of entities is allowed
> > options:
> >
> > 1.use elements a type x, b type x, c type x, d type x and e type y; place
> > them in the transaction as optional elements; the solution is clean but
> > requires rigid order of elements in the transaction.
>
> This is the correct solution in my opinion -- if order does not encode
> any information, then imposing an arbitrary order is good, not bad -- leaving
> order unconstrained encourages people to suppose that perhaps
>
> <container>
> <a>...</a>
> <b>...</b>
> </container>
>
> actually means something different from
>
> <container>
> <b>...</b>
> <a>...</a>
> </container>
>
> However, this is an FARP (Frequently Asserted Religious Position), and
> if you're not a devotee, you can use an <all> group to allow any
> order, e.g.
>
> <xs:all>
> <xs:element name="a" type="my:x" minOccurs="0"/>
> <xs:element name="b" type="my:x" minOccurs="0"/>
> <xs:element name="c" type="my:x" minOccurs="0"/>
> <xs:element name="d" type="my:x" minOccurs="0"/>
> <xs:element name="e" type="my:y" minOccurs="0"/>
> </xs:all>
>
> ht
> --
> Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
> Half-time member of W3C Team
> 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
> Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
> URL: http://www.ltg.ed.ac.uk/~ht/
> [mail really from me _always_ has this .sig -- mail without it is forged spam]
>
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