Individual items throughout the application can be selected by checking the box next to the particular item under the SELECT column header.
In addition, when you mouse over the SELECT column heading, you get three choices:
SELECT ALL, in which all items will be selected;
SELECT NONE, in which all items will be un-selected; and,
INVERT, in which the items that are already selected will be unselected and the ones that are not selected will be selected.