/sys$common/syshlp/DBG$HELP.HLB
DEBUG, CANCEL, BREAK, Qualifiers, /ALL

 *Conan The Librarian

    By default, cancels all user-defined breakpoints. When used
    with /PREDEFINED, cancels all predefined breakpoints but no
    user-defined breakpoints. To cancel all breakpoints, use CANCEL
    BREAK/ALL/USER/PREDEFINED.
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