Siemens SINUMERIK 840D Operating Manual page 341

Parameter Description
Left (machining to the left of the contour)
Radius 
compensation
Right (machining to the right of the contour)

off

A programmed contour can also be machined on the center-point path. In this case,
approaching and retraction is only possible along a straight line or vertical. Vertical
approach/retraction can be used for closed contours, for example.
Z0 Reference point Z (abs or inc)
Z1 Final depth (abs) or final depth referred to Z0 (inc) - (only for ∇ and ∇∇∇)
DZ Maximum depth infeed - (only for ∇ and ∇∇∇)
UZ Depth finishing allowance - (only for ∇)
FS Chamfer width for chamfering (inc) - (for chamfering only)
ZFS Insertion depth of tool tip (abs or inc) - (for chamfering only)
UXY Plane finishing allowance - (only for ∇ and G code)
Approach Planar approach mode:
Straight line:

Slope in space
Quadrant:

Part of a spiral (only with path milling left and right of the contour)
Semi-circle:

Part of a spiral (only with path milling left and right of the contour)
Perpendicular:

Perpendicular to the path (only with path milling on the center-point path)
Axis by axis
Approach strategy 
Spatial (only for "quadrant, semi-circle or straight line" approach)

R1 Approach radius - (only for "quadrant or semi-circle" approach)
L1 Approach distance - (only for "straight line" approach)
Retraction Planar retraction mode:
Straight line

Quadrant:

Part of a spiral (only with path milling left and right of the contour)
Semi-circle:

Part of a spiral (only with path milling left and right of the contour)
Milling
Operating Manual, 03/2010, 6FC5398-7CP20-1BA0
Programming technological functions (cycles)
8.3 Contour milling
Unit
mm
mm
mm
mm
mm
mm
mm
mm
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