G54-G59.3: Coordinate System Selection

G54 – coordinate system selection 1.
G55 – coordinate system selection 2.
G56 – coordinate system selection 3.
G57 – coordinate system selection 4.
G58 – coordinate system selection 5.
G59 – coordinate system selection 6.
G59.1 – coordinate system selection 7.
G59.2 – coordinate system selection 8.
G59.3 – coordinate system selection 9.

Each coordinate system stores its coordinates along the axes and the angle of rotation of the XY plane around the Z axis.

Additionally on the topic:
Working Coordinate Systems