Can-Bus Shield Questions

I notice that in the CAN.readMsgBuf(&len, buf); part of the code refers to the charecteds set above of length 0 and buffer 8, is that correct?

The sketch works great, but i am a bit confused as to this,

If i wanted to take a particular “Bit” of the message and do an if statement on it, can i use

if CAN.redMsgBuf([x]);

thanks

Rich