The `UnassignedMemberTreatment` shall allow to override back to `undefined` , e.g. if a containing type shall be treated as `AnyValue` but a nested type shall be fully specified. Thus there shall be a way to roll back to `undefined`. Separately, it may make sense to elevate the assignment to the `Package` level so that all `DataUses` in a `Package` are interpreted using the corresponding `UnassignedMemberTreatment` (somewhat dangerous but may be desirable in some cases). This breaks the locality to some extend, but as `DataInstances` already can define `UnassignedMemberTreatments` it is probably not that different. Finally, now that there are default values for members, it may make sense to allow the `UnassignedMemberTreatment` also on the type level and on `DataUse` level rather than `DataElementUse`.