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.