clear (or just c)
Issued without parameters, the clear command does pretty
heavy duty clearing of many of the GrADS internal settings. Parameters
can be added to limit what is cleared when using more advanced
features.
clear norset clears without resetting user options
clear events flushes the events buffer (e.g., mouse clicks)
clear graphics clears the graphics, but not the widgets
clear hbuff clears
the buffered display and turns off double buffer mode
clear button num clears button num
clear rband num clears rband num
clear dropmenu num clears dropmenu num
clear sdfwrite clears sdfwrite file name and attributes without resetting other user options (2.0.a3+)
clear mask clears contour label mask, which is enabled with the command 'set clab masked'(2.0.a7+)
clear shp clears shapefile output file name and attributes without resetting other user options (2.0.a9+)