/sys$common/syshlp/helplib.hlb PRODUCT, SHOW, OBJECT, Qualifiers, /BASE_SYSTEM  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /BASE_SYSTEM=(base-system-name[,...])

    Selects software products whose base system matches the one
    specified. The base system name identifies both a hardware
    platform and an operating system. The base system name AXPVMS
    denotes an OpenVMS Alpha product, VAXVMS denotes an OpenVMS VAX
    product, and VMS denotes a product applicable to either OpenVMS
    Alpha or VAX.

    Parentheses (())  are optional only when you specify a single
    base system name. They are required when you specify multiple
    base system names.