A link to the parent document which is expected to be of type Year.

List the stakeholders, organizations, or persons that participate in working on this todo.

This makes it easier to track todos on the participants' documents chronologically.

Add links to documents that refer to entities this event is concerned with.

If you are configuring a system or service, or follow a work instruction, this can be referenced for further information. It also identifies the entities unambiguously.