10.4.2.2 CAN frame data optimization (TX_DL = 8)
If this solution is used, the DLC does not always need to be 8. If the N_PDU to be transmitted is shorter
than 8 bytes, then the sender may optimize the CAN bus load by shortening the CAN frame data to
contain only the number of bytes occupied by the N_PDU (no padding of unused data bytes). CAN frame
data optimization can only be used for an SF, FC frame or the last CF of a segmented message.