This should be a simple one, at least for Stacho and Martin B. The metapost initialise definition seems to define the value u:, which turns up in lots of other places. if BaseScale <= 1: % 1:100 u:=14bp; v:=14bp; w:=12bp; fonts_setup(8,10,12,16,24); elseif BaseScale <= 2: % 1:200 u:=12bp; v:=12bp; w:=12bp; fonts_setup(7,8,10,14,20); elseif BaseScale <= 5: % 1:500 u:=10bp; v:=10bp; w:=12bp; fonts_setup(6,7,8,10,14); else: u:=7bp; v:=14bp; w:=10bp; fonts_setup(5,6,7,8,10); fi; It seems to be a standard measure against which lots of drawn entities are measured. In the above I think 1bp = 1/72" = 0.35mm approx. Is u: (and v: w: for that matter) intended to correspond to a particular drawn entity size in the finished pdf, or are they just arbitrary variables for which one can calculate the value of, using the code in the initialise definition? Cheers Bruce