XSL-FO filling the rest of a page with horizontal rule

Hello all,

I need to create an FO stylesheet that will fill the remaining space on
a page with horizontal lines when a certain element is encountered. This
is an application for printing tests for students, and a sample page
might contain an essay question, after which the rest of the page should
be filled with rules so that the student could write their answer.

Any ideas how to do this using XSL?

Thanks for any help.

Rick