/sys$common/syshlp/helplib.hlb RUN, Process, Qualifiers, /PRIORITY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /PRIORITY=n

    Requires ALTPRI (alter priority) privilege to set the priority
    higher than your current process.

    Specifies the base priority at which the created process
    executes.

    On Alpha, the value of parameter n is a decimal 0 to 63, where 63
    is the highest priority and zero is the lowest. Normal priorities
    range from 0 to 15; real-time priorities range from 16 to 63.

    On VAX, the value of parameter n is a decimal 0 to 31, where 31
    is the highest priority and zero is the lowest. Normal priorities
    range from 0 to 15; real-time priorities range from 16 to 31.

    The default priority is that of the current process.