[NTG-context] \setuplayout --- what do parameters mean?

All, When I see something like this: \setuplayout [topspace=10pt, header=40pt, headerdistance=20pt, height=middle, footerdistance=20pt, footer=0pt, bottomdistance=10pt, bottom=20pt, bottomspace=40pt, backspace=30pt, width=middle] I have a hard time working out what it means. I know I can do \showframe, but that doesn't indicate everything I need to see. Does anyone have a macro that shows ALL of these parameters in a visual way, similar to that on page 182 of the Latex User Guide, 2nd ed., Lamport?