Library /sys$common/syshlp/tracehlp.hlb START, /PRIORITY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    /PRIORITY=baspri

    The base priority of the detached process to be created.

    In order to avoid losing trace data it  is  advisable  to  run  the
    detached trace collector at a high priority.

    The default value is 8.

    Not valid with /LIVE qualifier.