footnote back reference?

OK, three days is enough to wrack my brains...



I have a footnote references like this:
  
    <FNR HREF="CH3TBL2FN1">&ast;</FNR> -or-
    <FNR HREF="CH3TBL2FN2">&ast;&ast;</FNR> etc..

And the footnotes are like this:

    <FN ID="CH3TBL2FN1">firstfootnotetext</FN>
    <FN ID="CH3TBL2FN2">secondfootnotetext</FN>

I want this:

    &ast;  firstfootnotetext
    &ast;&ast;  secondfootnotetext

Question:  how can I replace the @ID with the matching FNR text?



This is either really really simple, or...um, not.

BTW, my processor (xt-2002*) doesn't seem to like keys()

Thanks,

jb