/sys$common/syshlp/helplib.hlb Sys Parameters, RAD_SUPPORT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    (Alpha only) RAD_SUPPORT enables RAD-aware code to be executed
    on systems that support Resource Affinity Domains (RADs); for
    example, AlphaServer GS160 systems.

    A RAD is a set of hardware components (CPUs, memory, and I/O)
    with common access characteristics. For more information about
    using OpenVMS RAD features, see the OpenVMS Alpha Galaxy and
    Partitioning Guide.

    RAD_SUPPORT has the GEN attribute.