[NTG-context] Auto width and height on table cells

Hello, I want some tables to occupy 100% of \textwidth and \textheight and for all columns to be the same width except one or two that I want to specify and for all rows to be the same height except for one or two, that I want to specify as well.. For the moment, I'm doing it "manually", calculating column width as (\textwidth - width of fixed columns) / # rest of columns and row height as (\textheight - height of fixed rows) / # rest of rows I'm getting the result that I want, but it's a bit tedious. Is it possible to have ConTeXt do all those calculations for me? I haven't been able to figure it out from the manuals and the wiki. Thank you in advance. Regards, Ángel