I'm sure there's no official standard, but are there some guidelines for identifying and classifying browsers based on the User-Agent string they send?
+1
A:
According to the RFC 2616, here is the convention used by client to send their User-Agent.
User-Agent = "User-Agent" ":" 1*( product | comment )
Example:
User-Agent: CERN-LineMode/2.15 libwww/2.17b3
The header should contains a product token, and additional informations about version, used library by the client, etc.
But as you may know, User-Agent can totally be faked, so you can't really rely on it.
user-agents.org is a searchable database of user-agents
Boris Guéry
2010-04-30 09:13:59