messageNumber

The 0-based enumeration indicating the order in which this message was sent/received for each server.

Any two messages from the same client with the same messageNumber can be assumed to be identical.

The first client->server message would be 0 and the first server->client message would be 0. These are two separate counters.

This rule is sometimes broken. For instance, ConnectMessage_HELLO and ConnectMessage_HELLOD00D are not included in this count.