LinuxCNC M71 Invalidate Stored Modal State

M71 is a LinuxCNC M-code that invalidates modal state saved at the current call level by M70 or M73. After M71, that saved state cannot be restored, and a later M72 at the same call level will fail. If M71 is used in a subroutine protected by M73, a subsequent return or endsub will not restore modal state.

Source checked3/3 values · 2026-10-26

Specification

1 source

Language	gcode
Code	M71
Group	modal state
Syntax	M71
Dialect	LinuxCNC

Study notes

M71 operates at the current call level.
It invalidates modal state saved with M70 or by M73 at that level.
If a subroutine uses M73 and executes M71, a subsequent return or endsub will not restore modal state.
The document says the usefulness of M71 is dubious and it should not be relied upon because it might go away.