ZLM -- Draws graphics using the mouse
   ZLM BOX color height width  <keywords>
   ZLM CIRCLE color height width  <keywords>
   ZLM DRAW color  SMOOTH=
   ZLM FILL color height width  <keywords>
   ZLM FREE color
Parameters:
   BOX | draws a box
   CIRCLE | draws a circle or ellipse
   DRAW | draws a smooth, continuous line as you move the mouse
   FILL | draws and fills a box
   FREE | draws straight lines between points selected with mouse (def)
   color | graphics color level, use 0 to erase with FILL option (def=3)
   height | height of the box, circle or ellipse, in pixels
            (def=cursor height)
   width | width of the box, circle or ellipse, in pixels
           (def=cursor width)
Keywords:
   GRA= | graphics frame number to display output; valid only with MODE=N
          and BOX, CIRCLE, or FILL option (def=current)
   MODe=I | interactive mode (def)
       =N | non-interactive "batch" mode; draws shape centered at line
            and element position specified in POS keyword on the graphics
            frame specified with the GRA keyword; valid only with BOX,
            CIRCLE, or FILL option
   POS=line ele | TV line and element position to center the shape on;
                  valid only with MODE=N and BOX, CIRCLE, or FILL option
                  (def=current cursor position)
   SMOoth= | number of samples to take for the running average with the
             DRAW option; the range is 1-50; larger numbers produce
             smoother lines (def=3)
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