The default is to calculate from Cash date, but you can also choose to calculate from 3M date or a date of your choice. You must choose a valid end date. If the start date or end date are beyond the 3M date, then they must be a third Wednesday. The 3rd Wednesday dates are highlighted with an orange background. The selected date is shown in orange with a grey background.
When you have selected the dates you require, click the Get Data>> link. The spreads are calculated across all four clearing currencies and displayed with backwardation and contango indicators. It also shows for which settlement date the spread has been based on.