Absolute or incremental dimensioning (G90/G91)

G90 Absolute dimensioning (modal, default)
G91 Incremental dimensioning (modal)

In case of absolute dimensional input (G90), all the coordinate specifications are based on the coordinate basic origin, i.e. the coordinates in a traversing block specify the target position in the coordinate system.

In the case of incremental programming, the coordinate values are based on the target position of the preceding traverse block, i.e. the coordinates in a traversing block specify the path to be traversed.