HEIDENHAIN TNC 320 User Manual page 171

Characteristics of the fixed cycles
The TNC automatically positions the tool to the set-up clearance
before a cycle.
Each level of infeed depth is milled without interruptions since the
cutter traverses around islands instead of over them.
The radius of "inside corners" can be programmed—the tool keeps
moving to prevent surface blemishes at inside corners (this applies
to the outermost pass in the Rough-out and Side Finishing cycles).
The contour is approached on a tangential arc for side finishing.
For floor finishing, the tool again approaches the workpiece on a
tangential arc (for spindle axis Z, for example, the arc may be in the
Z/X plane).
The contour is machined throughout in either climb or up-cut milling.
The machining data (such as milling depth, finishing allowance and
set-up clearance) are entered as CONTOUR DATA in Cycle 20.
HEIDENHAIN TNC 320 171