INT 1A - WORD PERFECT v5.0 Third Party Interface - INSTALLATION CHECK           
	AX = 3601h
Return: DS:SI = routine to monitor keyboard input, immediately preceded by the
		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. string "WPCORP\0"
Notes:	WordPerfect 5.0 will call this interrupt at start up to determine if a
	  third party product wants to interface with it.  The third party
	  product must intercept this interrupt and return the address of a
	  keyboard monitor routine.
	Before checking for keyboard input, and after every key entered by the
	  user, Word Perfect will call the routine whose address was provided
	  in DS:SI with the following parameters:
		Entry:	AX = key code or 0
			BX = WordPerfect state flag
		Exit:	AX = 0 or key code
			BX = 0 or segment address of buffer with key codes
	See the "WordPerfect 5.0 Developer's Toolkit" for further information.
SeeAlso: INT 16/AX=5500h