This allows you to see when the next occurring date will be out of a set of custom data fields that you choose. This can be useful when you have custom data set to collect important dates and you want to know when the next important date would be. Once you select this as the Data Source you can then search for any number of custom data fields that are dates and add them as the Date Fields. One saved the column will show the next date. This data source option works well with Data Source: Label of next occurring date in set of data fields (1 row per action) which will show you the name of the data collection that has the most recent date.