VMS Help Sys Parameters, UAFALTERNATE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    UAFALTERNATE enables or disables the assignment of SYSUAF
    as the logical name for SYSUAFALT, causing all references
    to the user authorization file (SYSUAF) to be translated to
    SYS$SYSTEM:SYSUAFALT. Use of the normal user authorization file
    (SYS$SYSTEM:SYSUAF) can be restored by deassigning the system
    logical name SYSUAF. This parameter should be set on (1) only
    when the system is being used by a restricted set of users. You
    must create a user authorization file named SYSUAFALT prior to
    setting UAFALTERNATE to 1.

    UAFALTERNATE has the GEN and MAJOR attributes.