date model: date range

I'm looking at the [date-model-specification.md] (https://github.com/FamilySearch/gedcomx/blob/master/specifications/date-model-specification.md)

I have a question on the `Date Range` verse the Gedcom 5.5 `DATE_RANGE` and/or `DATE_PERIOD`.  It is not specified if the range means the event occurred on some date between start and end date, or the the event is continuous over the date range.  Gedcom 5.5 uses date range and period to differentiate between these two semantics.

1. the date-model-specification.md should specify the semantic meaning of the `Date Range`.
2. does the date-model-specification.md need to support both semantics?