* version 1.02 of marks.ellipse 1996 Mar 24
u%{
/ellipse { % x1 y1 x2 y2 xwidth ywidth
% define an ellipse
% centered at the average point of (x1, y1) and (x2, y2)
% with x and y axes defined in bases and bits respectively
% and xwidth wide, ywidth "high"
/ywidth exch def % in bits
/xwidth exch def % in bases
/y2 exch def % in bits
/x2 exch def % in bases
/y1 exch def % in bits
/x1 exch def % in bases
gsave
  x1 x2 add 2 div
  y1 y2 add 2 div
  translate
%
  xwidth charwidth 2 div mul % bases wide
  ywidth barheight 2 div 2 div mul % bits high
  scale
%
  0 0 % position
  1   % radius
  0 360 arc % arc of complete circle
  closepath
  fill
grestore
} def
!

u%{
/thin.bar { % x1 y1 x2 y2 xwidth ywidth
% define a bar
% centered at the average point of (x1, y1) and (x2, y2)
% with x and y axes defined in bases and bits respectively
% and xwidth wide, ywidth "high"
/ywidth exch def % in bits
/xwidth exch def % in bases
/y2 exch def % in bits
/x2 exch def % in bases
/y1 exch def % in bits
/x1 exch def % in bases
gsave
  x1 x2 add 2 div
  y1 y2 add 2 div
  translate
%
  xwidth charwidth 2 div mul % bases wide
  ywidth barheight 2 div 2 div mul % bits high
  scale
%
  1 0 0 setrgbcolor
  newpath
  -1 -1 moveto
  +1 -1 lineto
  +1 +1 lineto
  -1 +1 lineto
  -1 -1 lineto
  closepath
  fill
grestore
} def
!

* example: 1 base wide and 1 bit high:
* U -12.0 1.00   -12.0 2.0    1.0 1.0 ellipse