Re: [xml-dev] XML Schemas

[ht@inf.ed.ac.uk (Henry S. Thompson)]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Richard Lainchbury writes:

> If I have a xml document that looks like
>
> <?xsl version="1.0"?>
> <content>
>      <element type="one">
>            <file>This is only allowed if the element has @type equal
> to one</file>
>     </element>
>     <element type="two">
>            <text>This element is only allowed if the element has @type
> = 'two'</text>
>     </element>
> </content>
>
> Is it possible to put this restriction like this on with a schema?

Yes, if you spell 'type' as 'xsi:type' and declare
'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";' -- see the XML
Schema Primer [1].

> Is it even possible to put restrictions based on attributes?

General co-constraints involving element or attribute values are not
possible with W3C XML Schema, no.  Lots of specific constraints on
attribute presence/absence, and uniqueness and referential constraints
on their values, are possible.

ht

[1] http://www.w3.org/TR/XMLSchema-0/
- -- 
 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@inf.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]
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.6 (GNU/Linux)

iD8DBQFDYNoDkjnJixAXWBoRApBeAJ4hKjt1opuMM3j7n+HCNLWl7RNsIwCggnyK
z9HUHKHztMbjelnbJ3wyt7I=
=ZSzT
-----END PGP SIGNATURE-----