The general considerations for ObjectTypes also apply for EventTypes (which are specific ObjectTypes). As EventTypes typically use Properties, a reasonable extensibility mechanism across the Type-Hierarchy of EventTypes is to define specific Interfaces to be implemented.

Events provide information at a server-defined time, so unlike Variables, which a Client either reads or which are subscribed to with a specific sample interval, an Event is generated at a specific incident (e.g. when a part has been produced) and the data can be collected so that they are consistent and exactly from the time the incident occurred, enriched with data like the job id, etc. If for a long time period nothing happens, no event is generated, and if in a short time period many events occur, all those are generated and can be received by the Client.