VMS Help MACRO, VAX MACRO Assembler, Operand Formats, Absolute  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The address specified is the address of the operand.  The address
    is stored  as  an absolute virtual address (compare relative mode,
    where the address is stored as a displacement from the PC).
    Absolute  mode can be used with index mode.

    @#address

    address

    An expression specifying an address.