Data Group
A data group represents a set of records combined by a certain condition. Grouping grid data by items in tabular Views or data levels in Chart Views creates data groups. The following image displays data in the Table View grouped by two columns. It demonstrates five data groups. Each data group is addressed by its index, which specifies the position of this group.
Since you can group data by multiple items, data groups can have other data groups as children. In the image above data group 2 has data groups 3 and 4 as children. All data groups have parents. Data group 1 belongs to data group 0, for instance. Data groups 0 and 2 are displayed at level 0. They also have a virtual parent data group whose index is -1.