conn_handle

    OpenVMS usage:connection_id
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    The handle of the fully established (open) connection to send the
    data over.

 ios_icc

    OpenVMS usage:ios_status_block
    type:         structure IOS_ICC
    access:       write only
    mechanism:    by 32-bit or 64-bit reference (Alpha and Integrity
                  servers)
    I/O status block:

                           +2                       0
    -------------------------------------------------
    |       Undefined       |   Completion status   |
    -------------------------------------------------
    |                    Unused                     |
    -------------------------------------------------
                           +6                      +4

    Completion status values:

    SS$_NORMAL, SS$_EXQUOTA, SS$_INSFMEM, SS$_LINKABORT,
    SS$_LINKDISCON

 astadr

    OpenVMS usage:ast_procedure
    type:         procedure_entry_mask
    access:       call without stack unwinding
    mechanism:    by 32-bit or 64-bit linkage reference (Alpha and
                  Integrity servers)
    The AST routine to be executed when the operation completes.

 astprm

    OpenVMS usage:user_arg
    type:         quadword (unsigned) (Alpha and Integrity servers)
    access:       read only
    mechanism:    by 64-bit value (Alpha and Integrity servers)
    The parameter to be passed to the AST routine.

 send_buf

    OpenVMS usage:byte_stream
    type:         character-coded text string
    access:       read only
    mechanism:    by 32-bit or 64-bit reference (Alpha and Integrity
                  servers)
    The 32-bit or 64-bit address (on Alpha and Integrity server
    systems) of the buffer containing the data to be sent. The length
    of this buffer is specified by the argument send_len.

 send_len

    OpenVMS usage:buffer_length
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    The length (in bytes) of the data to be sent over the connection.
    This value specifies the length of the buffer send_buf. The
    maximum transmission size is 1MB.