CIGAL Reference Manual, Chapter 2 (Commands): ERASE
usage: erase [chan1 chan2 chan3 …]
ERASE clears the display memories. The CHAN arguments indicate which display channels to erase.
CHAN values: 0,1 text window 0 or 1 @0 - @7 PC image plane 0 -> 7 (entire screen) @10 ... Image processor image N >= 10 Image processor image N -2 colors on the current text screen (does not affect the text) -3 the current graphics drawing window (see [WINDOWS]) vecs Resets the vector graphics pointer, NVECS
If no argument is provided then the current active display will be erased. The active display depends upon how you have initialized the display (see INITIALIZE(2)) and which memory plane is being viewed (see VIEW(2)), but generally its meaning is obvious: if you are using an image processor, then the active display is the memory plane being viewed; if you aren't using an image processor, then the active display is the current text screen in text mode, or the graphics screen if you are in graphics mode.
Note: ERASE VECS simply resets the NVECS pointer to zero indicating that the active graphics vector list is empty; it does not in itself erase the graphics memory. To clear the screen you must also erase the active display screen as:
INITIALIZE(2), NVECS(4), VECS(4), VIEW(2), VMODE(4), WINDOWS(1)