From the GMA Techline
Subject: Classifying geotextiles — What is a “Class A” geotextile? (Ron, Maryland)
Reply: I don’t know, but it sounds pretty good!
I suspect that it comes from a state specification where product values are listed in an ascending or descending order, such as Class A, B, C, etc. or Class 1, 2, 3, etc.
Incidentally, all state DOTs have Web sites where you can look up these specs and their details.