Jason Hall , Aug 03, 2010; 06:35 p.m.
Basicly, when you meter a scene you will determine a certain exposure value. For example a sunny day will give you EV 15.
There is are a number of shutter and aperture values that will give you the same EV. So EV 15 (aka sunny 16 rule for a sunny day) will give you f16 with 1/125. or I can dial in f11 with 1/250 or f8 with 1/500. All of these combos with equal EV15, assumeing ISO 100 (or ISO 125, which was more common with film).
See the chart at the bottom of the page a linked to earlier