Breakpoints can be user defined or predefined. User-defined
    breakpoints are set explicitly with the SET BREAK command.
    Predefined breakpoints, which depend on the type of program
    you are debugging (for example, Ada or ZQUIT multiprocess), are
    established automatically when you start the debugger. Use the
    SHOW BREAK command to identify all breakpoints that are currently
    set. Any predefined breakpoints are identified as such.

    User-defined and predefined breakpoints are set and canceled
    independently. For example, a location or event can have both
    a user-defined and a predefined breakpoint. Canceling the user-
    defined breakpoint does not affect the predefined breakpoint, and
    conversely.

    To cancel only user-defined breakpoints, do not specify
    /PREDEFINED with the CANCEL BREAK command (the default is /USER).
    To cancel only predefined breakpoints, specify /PREDEFINED
    but not /USER. To cancel both predefined and user-defined
    breakpoints, specify both /PREDEFINED and /USER.

    In general, the effect of the CANCEL BREAK command is symmetrical
    with that of the SET BREAK command (even though the SET BREAK
    command is used only with user-defined breakpoints). Thus, to
    cancel a breakpoint that was established at a specific location,
    specify that same location (address expression) with the CANCEL
    BREAK command. To cancel breakpoints that were established
    on a class of instructions or events, specify the class of
    instructions or events with the corresponding qualifier (/LINE,
    /BRANCH, /ACTIVATING, /EVENT=, and so on). For more information,
    see the qualifier descriptions.

    If you want the debugger to ignore a breakpoint without your
    having to cancel it (for example, if you want to rerun the
    program with and without breakpoints), use the DEACTIVATE BREAK
    instead of the CANCEL BREAK command. Later, you can activate the
    breakpoint (with ACTIVATE BREAK).

    Related commands:

       (ACTIVATE,DEACTIVATE) BREAK
       CANCEL ALL
       (SET,SHOW) BREAK
       (SET,SHOW) EVENT_FACILITY
       (SET,SHOW,CANCEL) TRACE