INT 7A - Novell NetWare - IPX Driver - SEND PACKET
        BX = 0003h
        ES:SI -> Event Control Block (see below)
Notes:  returns immediately; IPX attempts to send the packet in the background
        this function is supported by Advanced NetWare 1.02+
SeeAlso: BX=0004h,BX=000Fh

Format of Event Control Block:
Offset  Size    Description
 00h    DWORD   Link
 04h    DWORD   -> Event Service Routine (00000000h if none)
 08h    BYTE    in use flag
                00h available
                FDh AES couting down delay time
                FEh awaiting packet reception
                FFh sending packet
 09h    BYTE    completion code (see below)
 0Ah    WORD    socket (big-endian)
                0452h Service Advertising Socket
                0456h diagnostics
                other
 0Ch  4 BYTES   IPX workspace
 10h 12 BYTES   driver workspace
 1Ch  6 BYTES   immediate local node address
 22h    WORD    fragment count
 26h    var     fragment descriptors
                Offset  Size    Description
                 00h    DWORD   -> fragment data
                 04h    WORD    size of fragment in bytes.
Notes:  ESR is a far procedure that is called when the ECB has been handled.
          On call, the in use flag is zero if the ECB has been handled,
          non-zero otherwise. If the flag is zero, the completion code holds
          the result of the event.
        the first fragment should start with an IPX header
        all fragments are concatenated and sent in one piece
        node address FFh FFh FFh FFh FFh FFh broadcasts to all nodes

Values for ECB completion code:
 00h success
 ECh remote terminated connection without acknowledging packet
 EDh abnormal connection termination
 EEh invalid connection ID
 EFh SPX connection table full
 F9h event should not be cancelled
 FCh cancelled
 FDh malformed packet
 FEh packet undeliverable
 FFh physical error

Event Service Routine called with:
        AL = caller's identity (00h = AES, FFh = IPX)
        ES:SI -> event control block
        interrupts disabled

Format of IPX header:
Offset  Size    Description
 00h    WORD    checksum (high byte first [big-endian])
 02h    WORD    length in bytes (high byte first) of total packet
 04h    BYTE    transport control
 05h    BYTE    packet type
                00h unknown packet type
                01h routing information packet
                02h echo packet
                03h error packet
                04h packet exchange packet (always use this one)
                05h SPX packet
                11h (used internally)
 06h 10 BYTES   destination internetwork address
 10h    WORD    destination socket (high byte first)
 12h 10 BYTES   source internetwork address
 1Ch    WORD    source socket

Format of Service Advertising Protocol Service Query Packet:
Offset  Size    Description
 00h 30 BYTEs   IPX header
 1Eh    WORD    query type (big-endian)
 20h    WORD    server type (big-endian) (see INT 21/AH=E3h"NetWare")

Format of Service Advertising Protocol Server Identification Packet:
Offset  Size    Description
 00h 30 BYTEs   IPX header
 1Eh    WORD    response type (big-endian)
                0002h general service
                0004h nearest service
 20h    WORD    server type (big-endian) (see INT 21/AH=E3h"NetWare")
 22h 48 BYTEs   ASCIZ server name
 52h  2 WORDs   network number (big-endian)
 54h  3 WORDs   node number (big-endian)
 5Ch    WORD    socket number (big-endian)
 5Eh    WORD    number of hops between caller and server (big-endian)