Doctype

I am trying to create a 3-row-table with HEIGHT 100%, where row 1 and 3 should have a FIXED height (50px),and row 2 a variable height, taking THE REMAINING x% of the page.

The doctype is set as <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>

Can anyone give me a solution???