http://www.carwindshields.info/winds...20the%20glass.
According to this.. markings that say anything about the quality or type of the glass are AS1 and "//" marking... and they are the same.
All other are
certification number for manufacturer (DOT)
Manufacturers model number ( M**)
European country that did the certification ( E1 is Germany)
Other markings on XYG im thinking are to do with country of origin:
DOT563 SHENZHEN AUTOMOTIVE GLASS MANUFACTURING P.R.O.C., CHINA
So other markings are maybe for Chinese market or for other asian markets. Who knows.
I have to note that Guardian and Carlex glass have same DOT22 :
DOT22 GUARDIAN INDUSTRIES CORP AUBURN HILLS, MI, USA