Graphical output in ASTERIX is controled by the Graphics-Control-Block (GCB) - a block of shared memory containing flags, switches and attribute values. All commands that produce graphical output interogate the GCB to determine the precise form of the output.
All quantities in the GCB can be set, cancelled and displayed by the command GSET. Commands in sub-packages such as image processing also set values in the GCB.
Values available for various plotting attributes are given in sub-sections below.