G90 Absolute Position Commands (Group 03)
G91 Incremental Position Commands (Group 03)
These G codes change the way the axis commands are interpreted. Axes commands following a G90 will move the axes to the machine coordinate. Axes commands following a G91 will move the axis that distance from the current point. G91 is not compatible with G143 (5-Axis Tool Length Compensation).
G90 Absolute Position Commands G91 Incremental Position Commands