Using the multivalue parameter control

Some tools allow you to specify multiple entries for a particular parameter. For example, you can include multiple datasets for the Input Features parameter in the Append, Union, and a number of other tools, or you can include multiple fields for the Statistics Field(s) parameter in the Dissolve and Summary Statistics tools. These parameters, as shown below, use the multivalue parameter control, which is a bit more complex than the majority of controls you'll use.

Illustration of multivalue parameter control

Adding multiple entries

Using the Input Features of the Union tool as an example, you can use any of the following ways to enter an input dataset to the list:

Multivalue control layer drop-down listMultivalue control type in pathMultivalue control drag and drop ArcMap layers

Managing the list

To remove an entry from the list, click the row to select it and click the Delete button Delete.

The entry order in the list may matter to some tools. To change the order, click the row to select an entry and click the Up Up or Down Down arrow button to move it in the list. The Up and Down arrow buttons are always available, even if the entry order doesn't affect the output of the tool. Read the documentation for the tool you're using to see if the order has any effect.

Multivalue control managing list

Editing other columns

In the entry list, there may be additional columns that give more control to the process. One example is the Ranks column in the Union tool. To change the rank for a particular feature entry, click the cell and edit the value.

Multivalue control Union ranks

Another example is the Statistic Type column in the Summary Statistics tool. In this case, when a field entry is specified, a red warning sign indicates that a statistic type is required for the field. You can click the cell and click the drop-down arrow. The available statistic types will be listed; you can now select a desired type.

Multivalue control stat field type