Footnotes at the end of a book

Dear docbookers,

The default xslt for html output places the footnotes at the end of a
component instead of a book.

Is it possible to move the footnotes to the end of the whole book by
processing the output html with special template and mode for "div"
with a "class" attribute of "footnote", or does one have to customise
the xslt stylesheets operating on the docbook source?

Klaus Schilling