1.   And a poetry reading meant audiences so small they helped redefine particle theory.

2.   A negative reading means that the number of manufacturers reporting deteriorating business conditions exceeded those reporting improved conditions.

3.   A negative index reading means manufacturers reporting deteriorating business outnumbered those reporting improved business conditions.

4.   A positive reading may mean a virus is present.

5.   A low reading meant that a company imposed few restrictions.

6.   A positive reading means that the number of manufacturers reporting improving business conditions exceeded those reporting deteriorating conditions.

7.   A negative reading means the number of companies reporting decreased activity was larger than those reporting stronger activity.

8.   A positive reading means the number of companies reporting increased activity was larger than those reporting weaker activity.

9.   Despite the decline, a positive reading still means the number of companies reporting increased activity was larger than those reporting weaker activity.

10.   Economists and investors watch the index because high confidence readings traditionally mean consumers feel secure enough to spend money and propel the economy.