Some vector data formats contain multi-part features. For example political boundaries may be represented with areas that are not contiguous, but share the same attributes, such as states that include islands.
These features may be grouped into multi-part polygons..
Grouped features will not be reflected in the feature count in the Control Center. Grouped features can be seen in the Metadata for layer under AREA GROUPS and also in the attribute table.
This option is available when area features are selected with the digitizer in the right-click context menu, under Advanced Feature Creation
The selected area features will be grouped into a single multi-part feature. The number of multi-part features will not be reflected in the feature count listed in the Overlay Control Center. The group count is listed in the Metadata and shown in the Geometry section of Feature
Info Tool. The individual areas will also receive an Area Group ID attribute.
This option is available when a multi-part area is selected with the digitzer tool. The option will be available in the digitizer right-click context menu under Advanced Feature Creation.
The selected multi-part features will be split into separate areas.
With the digitizer tool, it is possible to select only one polygon of a multi-part polygon. This option in the Advanced Selection options menu of the Digitizer top-level menu or context menu will select all polygons in the same multi-part group as the current selection.