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> -----Original Message-----
> From: ht@inf.ed.ac.uk [mailto:ht@inf.ed.ac.uk] On Behalf Of
> Henry S. Thompson
> Sent: Sunday, January 05, 2003 23:05
> To: Alessandro Triglia
> Cc: [XML-DEV]
> Subject: Re: [xml-dev] Questions on XML Schema "all" and
> RELAX NG "interleave"
>
>
> "Alessandro Triglia" <sandro@mclink.it> writes:
>
> > One concrete question I might ask is, If I have an "all" group of 3
> > elements in a schema, and an instance contains the 3
> elements in some
> > order (any order being valid), how much does it matter if a tool
> > re-orders the elements on reception, and presents them to
> the user in a
> > fixed order? Could I justify such a behavior of the tool by saying
> > that the order in an "all" group is not important? What are the
> > chances that the order *is* important and the user
> absolutely wants it
> > to be preserved?
>
> The chances ought to be high if the <all> group is being used
> responsibly (which it often isn't, in my experience). Let's
> approach this from the other side -- if an element is
> declared to contain a, then b, then c as children, then the
> relative order of a, b and c in an instance carries no
> semantics. From this Occam suggests that in cases where
> there is no intention to convey different semantics with
> different order among siblings, a sequence should always be
> used, to avoid potential misunderstanding. _If_ this
> argument is persuasive, then you should _only_ use <all> when
> order _does_ matter, in which case re-arrangement changes the
> meaning of the document and should be avoided.
>
> > Another possible question is, How does a user (either sending or
> > receiving) benefit, in general, in RELAX NG, from the ability to
> > interleave, say, elements A (multiple), B (multiple), and C
> (multiple)
> > of an "interleave", as opposed to sending all As, then all
> Bs, then all
> > Cs? Or possibly all Cs, then all Bs, then all As? Why is
> "interleave"
> > more useful than "all", and why is "all" more useful than
> "sequence"?
> > What do these things enable me to do, which a mere "sequence" does
> > not? Why do I need the extra flexibility?
>
> As per the above, if you need to reflect some underlying
> ordering, then you need a *ed choice or an all. Suppose for
> instance you have a queue of transactions to be processed,
> say some deposits and some withdrawals. If you wish their
> order in the queue to be represented by their order in the
> document, you can't simply put all the deposits first
> followed by all the withdrawals.
>
> Hope this helps
Many thanks, it surely helps.
I would like to hear other people's views as well.
Alessandro
>
> ht
> --
> Henry S. Thompson, HCRC Language Technology Group,
> University of Edinburgh
> W3C Fellow 1999--2002, part-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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