· User defined columns can only be added when there is an available data source.
· The user-defined columns are added in the topmost data source in the Data Sources list or in the joined or combined data source.
· An auto key can only be created once.
· Ranking requires a numeric source column.
· Time bucketing requires a time source column and each source column can only be used once.
· Numeric bucketing requires a numeric source column.
· Text grouping requires a text source column.
· The added user-defined column displays on the Data Preview with a pen symbol which allows its modification.