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+
        this function is nearly identical to BX=000Fh, except that it always
          copies the source address into the IPX header assumed to be at the
          beginning of the first fragment
SeeAlso: BX=0004h,BX=000Fh,INT 21/AH=EEh"Novell"

Format of Event Control Block:
Offset  Size    Description
 00h    DWORD   Link
 04h    DWORD   -> Event Service Routine (00000000h if none)
 08h    BYTE    in use flag (see below)
 09h    BYTE    completion code (see below)
 0Ah    WORD    (big-endian) socket number (see INT 7A/BX=0000h)
 0Ch  4 BYTEs   IPX workspace
 10h 12 BYTEs   driver workspace
 1Ch  6 BYTEs   immediate local node address
 22h    WORD    fragment count
 24h    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

Format of AES-ECB:
Offset  Size    Description
 00h    DWORD   Link
 04h    DWORD   ESR address
 08h    BYTE    in use flag (see below)
 09h  5 BYTEs   AES workspace

Values for ECB in use flag:
 00h    available
 E0h    AES temporary
 F6h    \ special IPX/SPX processing for v3.02+
 F7h    /
 F8h    IPX in critical section
 F9h    SPX listening
 FAh    processing
 FBh    holding
 FCh    AES waiting
 FDh    AES couting down delay time
 FEh    awaiting packet reception
 FFh    sending packet

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
 FAh    cannot establish connection with specified destination
 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    (big-endian) checksum
 02h    WORD    (big-endian) length in bytes of total packet
 04h    BYTE    transport control
 05h    BYTE    packet type (see below)
 06h 10 BYTEs   destination internetwork address
 10h    WORD    (big-endian) destination socket
 12h 10 BYTEs   source internetwork address
 1Ch    WORD    (big-endian) source socket

Values for IPX 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    NetWare Core Protocol
 14h    Propagated Packet (for NetWare), NetBIOS name packet
 15h-1Eh experimental protocols

Format of Service Advertising Protocol Service Query Packet:
Offset  Size    Description
 00h 30 BYTEs   IPX header
 1Eh    WORD    (big-endian) query type
                0001h general find service
                0003h find nearest server
 20h    WORD    (big-endian) server type (see INT 21/AH=E3h"NetWare")

Format of Service Advertising Protocol Server Identification Packet:
Offset  Size    Description
 00h 30 BYTEs   IPX header
 1Eh    WORD    (big-endian) response type
                0002h general service
                0004h nearest service
 20h 64N BYTEs  server entries (1-7) (see below)

Format of SAP server entry:
Offset  Size    Description
 00h    WORD    (big-endian) server type (see INT 21/AH=E3h"NetWare")
 02h 48 BYTEs   ASCIZ server name
 32h  2 WORDs   (big-endian) network number
 34h  3 WORDs   (big-endian) node number
 3Ch    WORD    (big-endian) socket number
 3Eh    WORD    (big-endian) number of hops between caller and server

Format of Routing Information packet:
Offset  Size    Description
 00h 30 BYTEs   IPX header
 1Eh    WORD    operation (0001h request, 0002h response)
 20h 8N BYTEs   network entries (1-50) (see below)

Format of RIP network entry:
Offset  Size    Description
 00h    DWORD   network number (FFFFFFFFh = general request)
 04h    WORD    (response) number of hops
 06h    WORD    (response) number of clock ticks to reach destination

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