sigarg

    OpenVMS usage:signal array
    type:         vector_longword_signed
    access:       read only
    mechanism:    by reference
    Address of the signal array for the given arithmetic exception.

 mcharg

    OpenVMS usage:mech array
    type:         vector_quadword_unsigned
    access:       read only
    mechanism:    by reference
    Address of the mechanism array for the given arithmetic
    exception.

 buffer

    OpenVMS usage:vector_quadword
    type:         vector_quadword_unsigned
    access:       write only
    mechanism:    by descriptor
    Four-quadword buffer to receive additional exception context.
    The buffer argument is the address of a descriptor that points to
    this buffer.