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"Rawlings, Matthew BGI UK" <Matthew.Rawlings@b...> writes:
> Is element sequence order significant in XML 1.0? I can see no clear guide
> from the specification - does omission mean significant or not significant?
>
> Given the example below is it reasonable if told in advance to attach
> significance, .e.g age order or grade order, to the set of brothers?
>
> <brothers>
> </matthew>
> </james>
> </luke>
> </david>
> </borthers>
>
> I understand that attribute sequence order is not significant in XML. This
> is clear to me from the specification.
Without looking at the DTD you can't tell. Somewhat
counter-intuitively, if the DTD says:
<!ELEMENT brothers (matthew,james,luke,david)>
then you can infer that order is _not_ significant, since the grammar
gives you no choice.
If on the other hand it says:
<!ELEMENT brothers (matthew|james|luke|david)*>
then you can infer that order _may_ be significant. Unfortunately,
you get the possibility of multiple instances as well.
In SGML (and in XML Schema [1]) you can say
<!ELEMENT brothers (matthew & james & luke & david)>
which again allows you to infer that (since the elements can occur in
any order) that order _may_ be significant.
Hope this helps,
ht
[1] http://www.w3.org/XML/Schema.html
--
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
W3C Fellow 1999--2001, 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@c...
URL: http://www.ltg.ed.ac.uk/~ht/
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