[NTG-context] Margin definition trouble.

Hello, I define my margins like so: % Papersize is 'letter' \setuppapersize[letter][letter] % CIT thesis regulations: 1 in margins, 1.5 in on the binding side % Johannes: no footer \setuplayout[ margin=1in, backspace=1.5in, footer=0in ] but the margins on top, bottom and right differ significantly from 1 in (ca. 1 in 3/16) and on the left from 1.5 in (ca. 1 in 11/16). This is in the printout. Do I have to go adjusting this arbitrarily, printing it and checking manually? Can anybody tell me what I'm doing wrong? Joh