Library /sys$common/syshlp/dbg$help.hlb DEBUG, CANCEL, TRACE, Qualifiers, /PREDEFINED  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Cancels a specified predefined tracepoint without affecting any
    user-defined tracepoints. When used with /ALL, it cancels all
    predefined tracepoints.