HEIDENHAIN ITNC 530 - 6-2010 DIN-ISO PROGRAMMING User Manual page 308

Do not include points when executing non-
compensated line blocks: M124
Standard behavior
The TNC runs all line blocks that have been entered in the active
program.
Behavior with M124
When running non-compensated line blocks with very small point
intervals, you can use parameter T to define a minimum point interval
up to which the TNC will not include points during execution.
Effect
M124 becomes effective at the start of block.
The TNC automatically resets M124 if you select a new program.
Programming M124
If you enter M124 in a positioning block, the TNC continues the dialog
for this block by asking you the minimum distance between points T.
You can also define T through Q parameters (see "Principle and
Overview" on page 254).
308 Programming: Miscellaneous Functions