You can specify whether a field in the filter area (filter area: The part of PivotTable or PivotChart view that contains filter fields.) will allow single or multiple selection. In single-selection mode, selecting an item (item: A unique element of data within a field. When a lower level of items is available for display in a PivotTable list or the field list, an expand indicator (+) appears beside the item.) automatically clears the previous selection. In multiple-selection mode, when you select an item, previously selected items remain selected.