It might be LOF (Libby Owens Ford)
Any safety glass has two different ratings. AS1 or AS2. AS1 is used in the windshield and AS2 in the back glass or door glasses. It the thickness of the vinyl that gives it the rating
Just thinking about it. Might be AS2 that has to be used in the windshield and AS1 everywhere else. Like I say it's been a long time. Thinking at least 35 years at least.