DVeop	(c) Copyright 1991 Ralf Brown

DVeop is a support program for DVdevload and any other XDI drivers run inside
DESQview windows which require notification on process termination.

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DVeop API:
     XDI function 01h (driver custom function) on INT 2Fh
     Call with: AH = XDI multiplex number (usually DEh)
		AL = 01h
		BX = 5242h ("RB", indicates a program by Ralf Brown)
		CX = 656Fh ("eo")  \
		DX = 7000h ("p",0) / identifies DVeop
     Returns:	AX = 5242h ("RB") if installed
		ES:BX -> DVeop entry point
		CX = version (CH = major, CL = minor)

     DVeop entry point
     Call with: ES:DI -> FAR function to be called when window closes
			or 0000h:0000h to remove callback
     Return:	AX = status
		    0000h failed (callback table full or attempted to
				  remove nonexistent callback)
		    0001h successful
			  ES:DI -> previous callback function
		BX,CX,DX destroyed
     Note:	If the previous callback function is not 0000h:0000h,
		the new callback function must chain to the previous
		function.

     The callback function is called with a simulated interrupt call
     with BX and DX as on entry to XDI function 05h (process
     termination), and must preserve all registers.  It should perform
     a far jump to the previous callback function after performing its
     processing, or an IRET if the previous callback address is
     0000h:0000h.