If SelectMultiple is set, then the Operation is executed for each selected choice. When this is set, the Select button text or Select column header in displayed lookup forms is changed to the name of the operation. The SelectImageKey in displayed lookup forms is also changed to the name of the Operation.

If this is left blank, then the name and header show Select. In this case selected object(s) is(are) placed in the bound many collection, and no operation is executed. A special case is the name "Show". In this case, the name need not be fully qualified, and the PaneName and DisplayLayout properties are used to determine where and how the selected object(s) are shown.