📅 Original date posted:2016-09-10 📝 Original message: Payments unexpectedly fragmented into multiple LN channels are trickier than transactions spending multiple UTXOs. If Alice pays Bob using multiple channels to fund one payment, then Bob's accounting procedures might need time-based heuristics to join separate LN transactions. Wherever payments might fragment, some reassembly protocol support, like BIP 70's merchant_data field, should be available. Every wallet should be assisting with this accounting. Since it's a low-level protocol, a varint should suffice. Since we didn't need to bring in X.509 yet, call it payment_id. Lack of a payment_id could, if tolerated at all, be considered a "don't fragment" request.