RTR replaced by RRS

As there are no Remote Frames for CAN FD the RTR bit is not necessary and is substituted by the always dominant Remote Request Substitution bit (RRS). Start of Frame (SOF), Identifier and Identifier Extension Bit (IDE) remain unchanged. Also at the end of the CAN FD frame the Acknowledge Bit (ACK), the corresponding Delimiter (DEL), the End of Frame (EOF) as well as the Intermission Field (ITM) remain as in traditional CAN frames.

The modifications of CAN FD compared to traditional CAN take place between the IDE bit and the Acknowledge bit.