id in an XML = id in another XML

[wxdqz]

I would like to specify in an XML file that an element id is the same than another element in another XML file.


File1.xml :
------------

<book id="001">
<ref href=http://www.webdeveloper.com/forum/archive/index.php/"File2.xml"/>
</book>



File2.xml :
------------

<object id="001"/>




I would like to find a way to say with the ref element that there is a link between id. Maybe that xlink can do something like this but i didn't find it.

So do you know if there is something with xml to say that id from two different files represents the same things ?

thanks.