Cardano block number that tells since which block the update is enforced
protocolVersion
New major and minor version to be announced, If major value changes, the node MUST stop issuing and reading operations, and upgrade before effective_since because the new protocol version. If minor value changes, the node can opt to not update. All events published by this node would be also understood by other nodes with the same major version. However, there may be new events that this node won't read