What do labels "fat-free" and "low calorie" mean?

Terms like these are on many food packages. Here are some definitions based on one serving of a food. If you eat more than one serving, you will go over these levels of calories, fat, cholesterol, and sodium.

Calorie-free: fewer than 5 calories
Low calorie: 40 calories or fewer
Reduced calorie: at least 25% fewer calories than the regular food item has
Fat free: less than ? gram of fat
Low fat: 3 grams of fat or fewer
Reduced fat: at least 25% less fat than the regular food item has
Cholesterol free: fewer than 2 milligrams cholesterol and no more than 2 grams of saturated fat
Low cholesterol: 20 milligrams or fewer cholesterol and 2 grams or less saturated fat
Sodium free: fewer than 5 milligrams sodium
Very low sodium: fewer than 35 milligrams sodium
Low sodium: fewer than 140 milligrams sodium
High fiber: 5 grams or more fiber