Dynamic bandwidth control

I have a question about category follow by below configuration.

 

when CLIENT_ACCEPTED {

 

set mycookie [IP::remote_addr]:[TCP::remote_port]

 

BWC::policy attach bwc_dynamic_policy200 $mycookie

 

}

 

 

How did iRule know IP/port is HTTP or P2P in category?

 

[Category name is a string that we define.]