> 2017-08-05T12:00:00 would be: 2017-08-05T.5
Well …, within the same time zone offset, but not necessarily within the same time zone. Think of a day (from 00:00 to 24:00) at a place where you change summer from / to winter time. Is the middle of the day always at 12:00, then?
Anyway, I think we would need to consider what we REALLY mean with 2017-08-05 in EACH use case: day precision OR the period of a day? I believe that things would clarify, then.