From: Saašha Metsärantala
> I would like to ask whether we need CONTEXTUAL duration AS OF #005? Is
> there a point with a start-duration interval (as of #005) if it always
> can be rewritten as a start-end interval as of #004?
Yes it seems that we're not sure that we have any use case for duration, either contextual or standalone, and, given the complexity with respect to its normalization, we should consider eliminating it from the spec.