It would be useful to keep documentation on what software (app or website) version an event was first introduced and decommissioned.

Why?

1 - Especially in the case of apps, we don't want to archive events that are decommissioned. The events are not available in the latest version of the app but older versions are still being used in the wild so it's useful to keep trace of what they are.

2 - Even in case of web applications, we still want to retain the description of past events to understand them.

3 - Be able to filter out all decommissioned and only see the current tracking plan

4 - Knowing when an event was first available can help analysts quickly understand how to work on a metric, rather than having to look in the data first