you could write a program that redefines the open command an example pseudo code would be:
Code:
;select file to open
;make a copy of the file renaming it with a txt extension
;read the first line of the file
;if a wcmatch = particular version
(progn
;display message box
;if message box = ok
;open drawing normally
;if not cancel command
);end progn
;if not continue on normally
;close and erase the txt file created
although I dont know if Lisp allows you to open that drawing and it doesnt prevent users from opening in explorer