Siemens SINUMERIK 840Di sl Programming Manual page 23

Turning:
Reference points
They are:
M
A
W
B
R
Fundamentals
Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
Machine zero
Blocking point. Can coincide with the workpiece zero point
(only turning machines).
Workpiece zero = Program zero
Start point. Can be defined for each program.
Start point of the first tool for machining.
Reference point. Position determined by cams and measuring
system. The distance to the machine zero M must be known, so
that the axis position can be set at this place exactly on this value
Fundamental Geometrical Principles
1.2 Position of zero points
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