Int 21 Fn 4402  U - LAN Manager - Tcpdrv.dos - API                         [N]

   AX = 4402h
   BX = file handle referencing device "TCPDRV$"
   CX = 0019h
   DS:DX -> buffer containing request block

Return: CF clear if successful
       buffer filled
   CF set on error
       AX = error code (01h,05h,06h,0Dh) (see AH=59h)
Program: TCPDRV.DOS is the low-level device driver supporting LAN Manager's
     TCP/IP protocol stack

Format of request block:
Offset Size    Description
 00h   BYTE    (call) function number
       00h initialize ???
       06h get ???
       07h get ???
 01h   BYTE    (call) 00h
       (return) error code if error, unchanged if successful
 02h   WORD    signature 4354h ('CT')
---function 00h---
 04h   DWORD   (call) pointer to ??? FAR function
       function is called with ES:BX -> device driver request used to
         invoke this function
 08h  4 BYTEs  ???
 0Ch   DWORD   (call) pointer to ??? record, WORD at offset 22h is read
 10h   DWORD   (return) -> ??? buffer if 0000h:0000h on call
---function 06h---
 04h  4 BYTEs  ???
 08h   DWORD   (return) pointer to ???
---function 07h---
 04h   DWORD   (return) pointer to ??? record