Provide a variable for the date of recording of a track. This needs to be derived from relationships. The date of recording is supposed to be set for:
- recording - place relationships of type "recorded at"
- recording - event relationships of type "recorded at"
- recording - area relationships of type "recorded in"
- recording - workrelationships of type "performance"
- What to do when there are multiple relationships, but they disagree? Use the earliest date?
- Is there any other way to store the recording date?