Programmable mirror imaging is used to turn on or off any of the axes. When one is ON, axis motion may be mirrored (or reversed) around the work zero point. These G codes should be used in a command block without any other G codes. They do not cause any axis motion. The bottom of the screen will indicate when an axis is mirrored. Also see Settings 45 through 48 for mirror imaging.
The format for turning Mirror Image on and off is:
G101 X0. = Will turn on mirror imaging for the X axis.
G100 X0. = Will turn off mirror imaging for the X axis.