INT 61 - Banyan VINES - "Soclose" - CLOSE A SOCKET
        AX = 0001h subfn 0004h
        DS:DX -> communications control block (function 0004h)
Return: AX = status (00h-0Ah,97h) (see AX=0001h/SF=0002h)
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,INT 15/AX=DE2Eh

Format of control block:
Offset  Size    Description
 00h    WORD    0004h
 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    socket identifier

.