Accounting Policies
  
What policy are you using to estimate the cost of your inventory? FIFO? Or LIFO? How fast are you depreciating your tech? You own a bunch of land with known gold reserves. The price of gold has shot up in the last three years. Do you keep that land value steady, or is your policy to re-adjust it every year? Whatever policies you set, you have to stick with them and remain with them for the duration...or restate with a new set of policies.
Why all the fuss? Because clever accountants can make opaque the bottom line earnings of their companies by changing rules/policies as they play the game, and that's not the way you play...fairly.