NET CARBS ? - Russell Stover Sugar Free Mint Patties (with Stevia Extract). What is Net Carbs/Legal?

I am trying to update my diary with the mint patties (in the Discussion Title) which has many entries in the data base but not finding an exact match. I noticed that there are matching Mint Patties Nutritional Facts except for showing 1 gram of Carb versus 17 grams of Carbs found on the package Nutrition Facts. Often the database entries with only 1 Carb references 'Net Carbs' (indicating Carbs minus Sugar Alcohol). Is there a diet legal reason for being worth only 1 Carb? (And when I subtract Carbs (17 per package) minus data base entry of Sugar Alcohol that equals 2 carbs???? Help, Thanking responders in advance).