VMS Help MACRO, /MIGRATION, Macros for 64-Bit Addressing, $IS 32BITS, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 quad_arg

    A 64-bit quantity, either in a register or in an aligned quadword
    memory location.

 leq_32bits

    Label to branch to if quad_arg is a 32-bit sign-extended value.

 gtr_32bits

    Label to branch to if quad_arg is greater than 32 bits.

 temp_reg=22

    Register to use as a temporary register for holding the low
    longword of the source value-R22 is the default.