hi,

mittra@j... a écrit :
> 
> if (TAG2 value is 1) then
>    <TAG3>some_value</TAG3>
> else
>    <TAG4>some_value2</TAG4>
> 
> Perhaps, XML Schema does it?
> 

this is exactly the way the Active Schema Language works : you can 
define dynamically the content model that suits your needs, potentially 
with the help of if-then-else statements

although ASL is experimental, it is implemented and works fine : you can 
use it for your own needs if you don't have to share your own schemas 
with third-party users ; ASL will allow you to express much more complex 
constraints than legacy schema technologies can (DTD, W3C XML Schema, 
RelaxNG, Schematron)

the implementation :
http://reflex.gforge.inria.fr/
the specification :
http://ns.inria.fr/active-tags/active-schema/active-schema.html
some tutorials :
http://reflex.gforge.inria.fr/tutorial-schemas.html

if you are new to XML, you'll have to understand namespaces in XML and 
learn XPath before (which are widely used in XML technologies)

some courses :
http://disc.inria.fr/perso/philippe.poulard/cours/01c-xml-namespaces.pdf
http://disc.inria.fr/perso/philippe.poulard/cours/04-xml-xpath.pdf
...if you are new to french, you'll have to learn french before :)

-- 
Cordialement,

               ///
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|      Philippe Poulard       |
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        Have the RefleX !