Getting values for attributes from a different XML.

Hi,
I dont really know if what I have in mind is feasible.
I have a stylesheet that is used for a number of
documents. This stylesheet is used to generate PDF
using FOP. Hence I am setting various attribute values
such as page size, margins, font-size, font-family etc
in the stylesheet. 
What I would like to know is that is there a way to
get the values of these paramters from another XML
file dynamically. I mean depending on the attribute
values in the XML I want to conver to PDF I would like
to get values from another XML for the above mentioned
attributes. I think this is like opening a XML file
through XSL and accessing the content in the XML.
I would like to know if this is feasible and if anyone
has tried something similar.
Thanks,
Abhi

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