how to access the main document from a node-set contex

Hi, I have run into another problem with my dependency sorting.
Basically what I'm doing is take elements from a document and
rearrange them into a result tree fragment. Then I run the
node-set funtion on them to get a useful new tree in which I
can do Xpath access. Now, I have several links in my generated
tree that point into the main document, but when I try
to follow them (with key or simple xpath search) I can never
access that original document because my context is this
generated node-set. How can I reach back to the original
document?

thanks for the hint,
-Gunther

--
Gunther Schadow, M.D., Ph.D.                    gschadow@xxxxxxxxxxxxxxx
Medical Information Scientist      Regenstrief Institute for Health Care
Adjunct Assistant Professor        Indiana University School of Medicine
tel:1(317)630-7960                         http://aurora.regenstrief.org