The following commands are used to control and monitor program
    execution:

    GO                     Starts or resumes program execution
    STEP                   Executes the program up to the next line,
                           instruction, or specified instruction
    (SET,SHOW) STEP        (Establishes, displays) the default
                           qualifiers for the STEP command
    (SET,SHOW,CANCEL)      (Sets, displays, cancels) breakpoints
    BREAK
    (ACTIVATE,DEACTIVATE)  (Activates, deactivates) previously set
    BREAK                  breakpoints
    (SET,SHOW,CANCEL)      (Sets, displays, cancels) tracepoints
    TRACE
    (ACTIVATE,DEACTIVATE)  (Activates, deactivates) previously set
    TRACE                  tracepoints
    (SET,SHOW,CANCEL)      (Sets, displays, cancels) watchpoints
    WATCH
    (ACTIVATE,DEACTIVATE)  (Activates, deactivates) previously set
    WATCH                  watchpoints
    SHOW CALLS             Identifies the currently active routine
                           calls
    SHOW STACK             Gives additional information about the
                           currently active routine calls
    CALL                   Calls a routine