Hello Chris, I'm thinking about how I would implement piggybacking. Is it better to combine DL_ACK and DL_DATA in the header and somehow seperate them at the other end, or is it best to make a seperate FRAMEKIND, like DL_DATA_ACK, that signifies that data and an acknowledgement has been sent? This is kinda outside the scope of the lab, but if it's the latter, how would this work if I wanted to combine more than just acknowledgements and data? For example, if I had 4 different frame types that could all piggyback each other, I would have an additional 6(?) things in the FRAMEKINDs enum. This would explode by a huge amount as I have more frame types, or if I allow more than 2 frame types to piggyback each other. Would you use bitwise flags (I think that's what they're called) instead? Thanks