Dave Pawson wrote:

Simple question, if I want to use fxsl library from 3 different
places on my machine,
Must I have literal strings in the href attribute, or can I
vary it.

   But in that case you do not have to be able to change the URI
within the same import statement.  You have to write the correct
import URI in each of your 3 using stylesheets.  The FXSL
stylesheets can remain the same.

   Thus so far, I still do not see exactly why you need an AVT for
xsl:import/@href.

   If you don't want to use different URIs in the importing
stylesheets, you can also use a cataloging system or a packaging
system like the one from EXPath ;-)

--
Dave Pawson
XSLT XSL-FO FAQ.
http://www.dpawson.co.uk