ZmnSCPxj emphasizes the need for precision in terminology and defines a blockchain as a Merklized singly-linked list containing representations of transformations of state. While he does not consider Lightning Network a sidechain, he acknowledges that both federated sidechains and LN have a "federated" off-chain structure. He also explains that the security of LN is greater than typical federations as it requires consensus rather than a quorum.