What is the difference between AS1, AS2 and AS3 glass?

It seems there is a confusion in your question between glass classifications for automotive use (AS1, AS2, AS3) and AS2/AS3 protocols used in data interchange.

Let's clarify the differences between AS1, AS2, and AS3 glass classifications for automotive use:

1. AS1 Glass: This refers to laminated windscreens and side/rear windows with a light transmission of at least 70%. AS1 glass is typically used for front windshields because it provides clear visibility and meets safety standards.
2. AS2 Glass: AS2 glass also has a light transmission rate of at least 70%. However, it is used for all tinted glass with a transparency of at least 70%, excluding windshields. AS2 glass can be utilized in any part of the vehicle except the front windshield.
3. AS3 Glass: AS3 glass has a light transmission rate of not less than 70%, similar to AS1 and AS2. However, it is typically used in certain areas of specific vehicles. AS3 glass may have slightly different regulations depending on the jurisdiction but generally, it is acceptable only in areas not essential for driving visibility.

Now, as for AS2 and AS3 protocols used in data interchange:

• AS2 Protocol: AS2 (Applicability Statement 2) is a protocol used for secure and reliable data interchange over the internet. It ensures message integrity, confidentiality, and authentication. AS2 messages are typically transmitted over HTTP or HTTPS. MDNs (Message Disposition Notifications) can be transmitted synchronously over the same connection as the original message in AS2.
• AS3 Protocol: AS3, on the other hand, is not a widely known or adopted protocol compared to AS2. AS3 could refer to an alternate version or an extension of AS2, but it's not a standardized protocol in the same way AS2 is. Therefore, it's less common and may not have widespread support in data interchange scenarios.

In summary, AS1, AS2, and AS3 glass classifications refer to different standards for automotive glass transparency and usage, while AS2 and AS3 protocols refer to standards for secure data interchange over the internet, with AS2 being the more established and widely used protocol.