The variable context after a keyboard interrupt is that of the program unit in which the interrupt occurred. By typing the statement RETURN, the program context will revert to the next higher calling level. The RETALL command returns control to the main program level. If any doubt arises as to which program unit in which the interrupt occurred, the HELP procedure can be used to determine the program context. IDL checks after each statement to see if an interrupt has been typed. Execution does not stop until the statement that was active finishes; thus, considerable time can elapse from the time the interrupt is typed to the time the program interrupts.