Question about Including external stylesheets

This is a rather strange problem but I'll try and explain it as best I can.
In my client application, I am using a certain stylesheet to transform the
output from our app. server. Depending on the content of the XML I want to
include(import actually) one of several stylesheets dynamically. I've
noticed that it is not possible to use a variable in the call to an
xsl:include statement (I don't think) and certainly not with an import since
it has to be the first thing in the stylesheet. Does anyone have any ideas
about how I can link a stylesheet with another stylesheet dynamically? 

Here is another representation of what I'm trying to do...

top_level.xsl imports middle_level.xsl imports bottom_level.xsl

I want to be able to change out 'middle_level.xsl' depending on the content
I get back from the server. The goal is to have multiple 'panes' of the HTML
page, enabling the user to switch out the content he has shown in the middle
pane (middle_level.xsl).

Any ideas would be appreciated. I'll try and go into detail and answer any
questions if desired.

Brian Erickson
GE Smallworld

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