Do you know an intermediate web page description language?

I'm searching for an XML language, which allows you to describe web pages/portals in a very high abstraction level.
I need it for transforming different data oriented XML schemas to an intermediate representation which is in turn transformed to the final ouput format (html, wml, pdf, ...).

Here are some requirements for the language I'm looking for:
* High level abstraction of portal elements (e.g. menu, ads, search field, logo, registration area, content area, forms, actions, ...)
* Presentation neutral description of content elements
* Embeding of different namespaces
* Prevent to write transformations from every data oriented language to every presentation format

Here's what I found so far:

Data oriented:
* News Industry Text Format (NITF)
* NewsML
* PRISM
* DocBook
* Cocoon/Forrest Document DTDs

Presentation oriented:
* (X)HTML
* XSL:FO (for PDF, ...)
* WML

Presentation independent:
The following only satisfy my needs partly:
* XHTML 2.0
* Forrest site.xml
* Forrest Book.xml
* ? (if you know some standards or drafts which fit in here please write an email to the address 'andreas dot hochsteger at oeamtc dot at').

It's really curious, that I could not find something similar, since I think it was quite common to transform data into an intermediate format and this intermediate format into the needed output format instead of transforming from every data format into every output format directly :-|