INT 61 - Banyan VINES - "Sosend" - INITIATE OUTPUT EVENT
        AX = 0001h subfn 0002h
        DS:DX -> communications control block (function 0002h)
Return: AX = status (see below)
Note:   Banyan can use any interrupt from 60h through 66h.  The Banyan
          interrupt handler is identified by the string "BANV" in the four
          bytes immediately preceding the interrupt handler
SeeAlso: AX=0001h/SF=0001h,AX=0001h/SF=0005h

Values for status:
 0000h  successful
 0001h  service not installed
 0002h  invalid service ID
 0003h-000Ah reserved for BANV interface errors
 0097h  invalid socket identifier
 009Bh  destination node unreachable
 009Ch  message overflow
 009Dh  destination socket nonexistent
 00A2h  no more buffer space
 00A3h  timeout
 00B1h  resource disconnect

Format of control block:
Offset  Size    Description
 00h    WORD    0002h
 02h    WORD    pointer to argument block (see below)
 04h    WORD    error return code
                0000h successful
                0097h invalid socket ID
                00A2h no more buffer space
                00A3h timeout event
                00A5h resource not available
                00A6h internal communication failure
                00B1h resource disconnect
 06h  4 BYTEs   reserved

Format of argument block:
Offset  Size    Description
 00h    WORD    routine metric
 02h    WORD    error return code
 04h    WORD    socket identifier
 06h    WORD    pointer to send buffer
 08h    WORD    length of send buffer
 0Ah    WORD    flags
                bit 0: async request
                bit 1: reliable message
                bit 3: end of user message received
                bit 4: vectored request (if set, send buffer contains buffer
                        descriptors)
                bit 5: connection-specific receive
                bit 6: change to connection-specific receive mode
 0Ch 16 BYTEs   socket address (see below)
 1Ch    WORD    timeout value in multiples of 200ms
 1Eh    WORD    connection identifier
 20h    WORD    type of request
                0001h send message
                0002h establish a virtual connection
                0003h terminate a virtual connection

Format of buffer descriptor:
Offset  Size    Description
 00h    WORD    data segment
 02h    WORD    buffer pointer
 04h    WORD    buffer length
 06h    WORD    character count

Format of socket address for unreliable datagrams:
Offset  Size    Description
 00h    WORD    0003h     address family
 02h    DWORD   FFFFFFFFh network number
 06h    WORD    FFFFh     subnet number
 08h    WORD              local port number
 0Ah    BYTE    00h-0Fh   hop count
 0Bh  5 BYTEs   0000h     filler

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