Inside <dateoftrip> the date of beginning and end, and/or the duration of a dive trip is given. The only element inside <dateoftrip> is <datetime>.
<trip>
<datetime>
<trip>
see also <trip>
<!-- begin of trip on Sunday, May 11th, 2008, end on Saturday, May 31st, 2008 - diration 21 days -->
<!-- indication as start and end date, divided by a slash "/" -->
<datetime>2008-05-11/2008-05-31</datetime>
<!-- indication as start date and duration, divided by a slash "/" -->
<!-- (instead of "3W" it is also possible to write "21D") -->
<datetime>2008-05-11/P3W</datetime>
<!-- indication as duration with end date, divided by a slash "/" - in this case the time of arrival (15:30 hours) is given, too -->
<datetime>P3W/2008-05-31T15:30:00Z</datetime>