HEIDENHAIN TNC 320 User Manual page 264

Position display in the tilted system
On activation of Cycle 19, the displayed positions (ACTL and NOML)
and the datum indicated in the additional status display are referenced
to the tilted coordinate system. The positions displayed immediately
after cycle definition might not be the same as the coordinates of the
last programmed position before Cycle 19.
Workspace monitoring
The TNC monitors only those axes in the tilted coordinate system that
are moved. If necessary, the TNC outputs an error message.
Positioning in a tilted coordinate system
With the miscellaneous function M130 you can move the tool, while
the coordinate system is tilted, to positions that are referenced to the
non-tilted coordinate system.
Positioning movements with straight lines that are referenced to the
machine coordinate system (blocks with M91 or M92) can also be
executed in a tilted working plane. Constraints:
Positioning is without length compensation
Positioning is without machine geometry compensation
Tool radius compensation is not permitted
264 Cycles: Coordinate Transformations