INT 61 - Banyan VINES - "Sowait" - WAIT FOR ASYNCHRONOUS EVENT COMPLETION
        AX = 0001h subfn 0005h
        DS:DX -> communications control block (function 0005h)
Return: AX = status (see below)
Notes:  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
        returns results for all asynchronous operations invoked from the
          data segment used for this call
SeeAlso: AX=0001h/SF=0002h,AX=0001h/SF=0009h

Values for status:
 0000h  successful
 0001h  service not installed
 0002h  invalid service ID
 0003h-000Ah reserved for BANV interface errors
 00A2h  no more buffer space available
 00A3h  timeout event

Format of control block:
Offset  Size    Description
 00h    WORD    0005h
 02h    WORD    pointer to argument block (see below)
 04h    WORD    error return code
 06h  4 BYTEs   reserved

Format of argument block:
Offset  Size    Description
 00h    WORD    pointer to WORD event pointer
 02h    WORD    timeout in multiples of 200ms, FFFFh = infinite

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