INT 7A - Novell NetWare - IPXODI v2.12+ - IPX(Internetwork Packet Exchange) A low-level layer of Novell's NetWare networking software. GENERATE CHECKSUM
	BX = 0021h
	ES:SI -> ECB data (see #03810 at INT 7A/BX=0003h)
Return: ES,DS,SI preserved
	BX,BP corrupted, all other registers potentially destroyed
Notes:	the checksum and TransportControl fields of the IPX(Internetwork Packet Exchange) A low-level layer of Novell's NetWare networking software. packet are updated
	this function enables interrupts and is fully reentrant
SeeAlso: BX=001Fh,BX=0020h,BX=0022h,INT 2F/AX=7A2Fh