Xerox M20/M20i User Manual page 33

Interrupt Use to interrupt the current copy job to run a more urgent job.
Start Use to activate a job.
Stop Use to stop an operation at any time.
Clear/Clear All (AC) Press once to clear a current entry e.g. an incorrect number or character
entry. Press twice to clear all programmed settings, the display requests
confirmation.
Xerox CopyCentre C20, WorkCentre M20 and WorkCentre M20i User Guide Page 2-9