A computer-implemented method for performing by a node of a network of nodes for maintaining at least part of a distributed ledger maintained by the network of nodes is described. The method comprises maintaining at least part of the distributed ledger. The at least part of the distributed ledger is configured to store records and associated verification data for the records. The verification data for a record identifies: (i) a sequence of nodes in the network which received the intended record during a verification procedure; and (ii) the respective event state assigned by each node of the sequence of nodes to the intended record during the verification procedure.