buffer

    OpenVMS usage:address
    type:         longword (unsigned)
    access:       read/write
    mechanism:    by 32- or 64-bit reference
    The user buffer in which the alignment fault data is to be
    stored. The buffer argument is the 32- or 64-bit virtual address
    of this buffer.

 buffer_size

    OpenVMS usage:byte count
    type:         longword (signed)
    access:       read
    mechanism:    by value
    The size, in bytes, of the buffer specified by the buffer
    argument.

 return_size

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       write
    mechanism:    by 32- or 64-bit reference
    The amount of data, in bytes, stored in the buffer. The return_
    size argument is the 32- or 64-bit virtual address of a naturally
    aligned longword into which the service returns the amount of
    data, in bytes, stored in the buffer. The return_size argument is
    set to 0 if there is no data in the buffer.