All distances in the CGM file are in abstract units. The application
that reads the file determines the size of the final plot. By default,
the width of the final plot is assumed to be 6 inches (15.24 cm). This
distance is used to calculate the correct font size, and may be changed
with the width option. The keyword should be followed by the width in
points. (Here, a point is 1/72 inch, as in PostScript. This unit is
known as a "big point" in TeX.) Gnuplot expressions can be used to
convert from other units.
Example:
set terminal cgm width 432 # default
set terminal cgm width 6*72 # same as above
set terminal cgm width 10/2.54*72 # 10 cm wide
