Siemens SINUMERIK 840Di Function Manual page 752

Detailed Description
2.2 Zeros and reference points
Fig. 2-9
Fig. 2-10
2-22
Position of coordinate systems by machine zero M and workpiece zero W
Position of reference point in relation to machine zero
Axis Types, Coordinate Systems, Frames (K2)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0