xcall CCON {,flag}

xcall CCOFF

CCON.SBR enables or disables Ctrl+C. When called with no arguments, or if the argument passed has a non-zero numeric value, then it enables Ctrl+C. When called with an argument that evaluates to zero, it disables Ctrl+C and is therefore equivalent to CCOFF.SBR.

CCOFF.SBR disables Ctrl+C. This might be useful in a program at the start of a critical update sequence that you did not want the operator to be able to interrupt. It is also equivalent to SET NOCTRLC (from the dot prompt).