LEGEND:FRAME
(xlo,ylo) are the coordinates of the lower left corner of the frame box,
while (xhi,yhi) are coordinates of the upper right corner. If any of xlo,
ylo and xhi, yhi are not entered, these coordinates will be chosen with
the graphics crosshair. The default coordinates are (xlo,ylo) = (55,22.5)
and (xup,yup) = (78,45) expressed as percentages of the window. The units
for the coordinates are chosen by command qualifier:
\PERCENT -- means the coordinates are percentages of the window
\GRAPH -- means the coordinates are in graph units
\WORLD -- means the coordinates are in centimeters or inches,
as chosen by the SET UNITS command (default centimeters)