By default, the AllowMultipleValuesOnEnum property is False. If the AllowMultipleValuesOnEnum property is True, the EditEnum properties may display a checkbox for any predefined value in the enumeration that may be a bit combination. When user clicks the checkbox, the new value includes or excludes the clicked flag. The COM objects may allow bit combinations for predefined values. 

For instance, let's say that our control browses the AllowSelectObjects property of the Exontrol's eXG2antt component. The AllowSelectObjects property is of SelectObjectsEnum which allow bit combination of the following values:

• exNoSelectObjects, 0, The user can't select any object in the chart area
• exSelectBarsOnly, 1, The user can select bars only.
• exSelectLinksOnly, 2, The user can select links only.
• exSelectObjects, 3, The user can select any object in the chart.
• exSelectSingleObject, 16, If present, it specifies whether the user can select one or multiple objects. For instance, the exSelectBarsOnly Or exSelectSingleObject specifies that the user can select a single bar in the chart. The exSelectLinksOnly Or exSelectSingleObject specifies that the user can select a single link in the chart.
• and so on.

The exSelectSingleObject flag can be combined with any previously value that will indicates that the control allows single selection only in the chart. 

The following screen shot shows the ExPropertiesList control when the AllowMultipleValuesOnEnum property is True, and Chart.AllowSelectObjects property is exSelectSingleObject Or exSelectBarsOnly:

The following screen shot shows the ExPropertiesList control when the AllowMultipleValuesOnEnum property is False ( by default ), and Chart.AllowSelectObjects property is exSelectSingleObject Or exSelectBarsOnly.