The M67 is a manufacturer's model number for the piece of glass, which identifies the type of construction. The M number is unique to the manufacturer, so another manufacturer could have the same M number, but assigned to a different glass.
The "AS" number stands for "American Standard" (and I thought they made plumbing fixtures
). The number following the "AS" indicates the position in which the glass may be used, based on its optical quality. AS-1 is the clearest glass (at least 70% light transmission), is laminated, and can be used anywhere in a motor vehicle (typically just the windshield). AS-2 and AS-3 cannot be used for windshields.John