[Description] Provide available values to create a drop-down list that your users can choose from. This is a good way to ensure that only valid values are submitted in the dataset query. Select this option if the value for the parameter can be multiple values that are displayed in a drop-down list. Null values are not allowed. When this option is selected, check boxes are added to the list of available values in a parameter drop-down list. The top of the list includes a check box for Select All. Users can check the values that they want. If the data that provides values changes rapidly, the list the user sees might not be the most current. [Property] 
Allow multiple values