INT 11 - RainbowFAX v1.3 - SFENGINE API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes. - OPERATIONAL CONTROL
	AH = 77h
	AL = subfunction
	    01h request SFENGINE start
		Return: AX = 0001h
	    02h check if SFENGINE started
		Return: AX = 0000h or 0001h
	    03h request SFENGINE stop
		Return: AX = 0001h
	    04h check if SFENGINE stopped
		Return: AX = 0000h or 0001h
	    05h installation check
		Return: AX = 0001h
	    06h uninstall???
		BX:DX -> return address for successful uninstall???
		Return: (at caller's address)
			AX = 0000h
	    else
		Return: AX = FFFFh (invalid subfunction)
Return: ES:DX -> ASCIZA NUL-terminated ASCII string.	The ASCIZ string "ABC" consists of the four bytes 41h, 42h, 43h, and 00h.  Unless otherwise specified, maximum lengths given in the interrupt list do not include the terminating NUL. signature string "SFAX ENGINE V1.0"
		followed by internal data area???
SeeAlso: AH=78h,AH=79h,AH=7Ah,AH=7Ch
Index:	installation check;RainbowFAX|installation check;SFENGINE
Index:	uninstall;RainbowFAX|uninstall;SFENGINE