A user can use a pointing device to select value set items. The SAA CUA Guide to User Interface Design defines mouse button 1, the select button, to be used for selecting items. This definition also applies to the same button on any other pointing device.
An item can be selected by moving the pointer of the pointing device to the item and clicking the select button. When this happens, a black box is drawn around the item to show that it has been selected. The black box is called selected-state emphasis. In addition, the selection cursor is drawn inside the black box.