Abstract: A complex computing system has a plurality of nodes interconnected by channels through which data messages are exchanged. The underlying principle is that after arrival at a node of a message, delivery of that message is delayed until after delivery and consequences of all more senior messages which affect the node. The messages are progressively timestamped at each node so that each time stamp contains generation by generation indicators of the origin of the associated message. The seniority of that message is uniquely determined thereby and total ordering of the messages can be achieved. When comparing timestamps for such ordering, comparison of respective generation indicators is necessary only until there is a distinction.