> Now, how do I create a schema to represent this considering that is is
> indexed by the attribute value of id? 

w3c xml schema can't really do anything about that as it can't express
different content models for section elements depending on its id
attribute, but Relax NG or schematron (for example) could be used to
express constraints on such a document type.


even w3c schem can express some things, it can't base the content model
of child elements based on the attribute value but it can base it on its
possition in the hierarchy, so you could for example state that the top
level section has to have id="report definition" and that its section
children have to have id="officers" or ... and that their section children
have to have ids "name" or  "appointment date" etc.
You couldn't though express requirements such as 
<section id="name"/> comes before <section id="date of birth"/>
in W3C schema, unlike relax ng or schematron.

David

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