CONTOUR:contour_labels

size

 The size of the contour labels is %LABSIZ.  If labels are not desired on
 the contours, use the SET command to set %LABSIZ to zero before entering
 the CONTOUR command.

separation

 The separation between contour labels is controlled with CNTSEP or
 %CNTSEP, which can be changed with the SET command.  If %CNTSEP is set,
 the separation is a percentage of the height of the window, that is,
 YUWIND-YLWIND. If CNTSEP is set, the separation is expressed in inches
 or centimeters, depending on the units type as set with the SET UNITS
 command. The default is %CNTSEP = 50.