Periods

Definition of periods:

Start: From dateTime where the dateTime is included in the period.
End: To dateTime where the dateTime is excluded from the period.

Example. Period for 24 hours starting at midnight on may 1st 2015:

Start: 2015-05-01T00:00:00+02:00
End: 2015-05-02T00:00:00+02:00