A schematic presentation of a sampling event using a CTD and several Niskin bottles mounted on a rosette. In the example the bold rectangles are sampling events, the dashed rectangles measurements or facts, the grey rectangles are occurrences. All CTD readings taken at the same time at the same depth are grouped together into a child event of the event "CTD". Data derived from the CTD measurements like "mixed layer depth" can be linked directly to the event "reading depth". Each sample taken by a Niskin bottle placed on the roset can be considered a different child event "niskin" of the event "cast". Measurements of the water collected by the Niskin bottle can be linked to these "niskin" events.