A DefaultBoolean enumeration value that specifies whether an end-user can group data by the current column.
End-users are allowed to group data if the grid's GridControlBase.AllowGrouping property is set to true. Individual columns provide the AllowGrouping property, allowing the default behavior specified by the grid, to be overridden. Setting this property to 'True' or 'False' overrides the default behavior. This can be useful when it is required to prevent an end-user from grouping data by values of specific columns.