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

       /AFFINITY (Alpha only)
       /NOAFFINITY

    Allows bits in the kernel thread affinity mask to be set or
    cleared individually, in groups, or all at once. This qualifier
    is mutually exclusive with the /CAPABILITY qualifier.

                                   NOTE

       The SET PROCESS/[NO]AFFINITY command fails if none of the
       specified CPUs has the capabilities required by the process.

    The /NOAFFINITY qualifier clears all affinity bits currently set
    in the current or permanent affinity masks, based on the setting
    of the /PERMANENT qualifier. Specifying the /AFFINITY qualifier
    has no direct effect, but merely indicates the target of the
    operations specified by the following secondary parameters:

    /SET=(n[,..Sets affinity for currently active CPUs defined by the
               CPU IDs n, where n has the range of 0 to 31.
    /CLEAR=(n[,Clears affinity for currently active CPUs defined by
               the position values n, where n has the range of 0 to
               31.
    /PERMANENT Performs the operation on the permanent affinity
               mask as well as the current affinity mask, making the
               changes valid for the life of the kernel thread. (The
               default behavior is to affect only the affinity mask
               for the running image.)

    The secondary qualifiers can all be used at once as long as the
    affinity bits defined in the /SET and /CLEAR parameters do not
    overlap.

    The privileges required to execute the SET PROCESS/AFFINITY
    command match those required by the $PROCESS_AFFINITY system
    service. ALTPRI is the base privilege required to make any
    modifications, and the only privilege required to modify the
    current owner's kernel thread. Modifications within the same UIC
    group require GROUP privilege. Modifications to any unrelated
    kernel thread require WORLD privilege.

    As with the other SET PROCESS qualifiers, the bit operations
    occur on the current process if no /IDENTIFICATION qualifier
    or explicit process name parameter is specified. Specifying a
    process name does not imply that all kernel threads associated
    with the process are affected; the SET PROCESS command affects
    only the initial kernel thread of a multithreaded process.