Here's the definition that's on our security deposit page, which doesn't get into the nitty-gritty: Normal wear and tear is a term that Wisconsin law does not define.
(3)Protein Fat-Free Percentage, Protein Fat-Free Content, PFF Percentage, PFF Content or PFF of a product means the meat protein (indigenous to the raw, unprocessed pork cut) content expressed as a percent of the non-fat portion of the finished product.
The FSIS draws its authority from the Federal Meat Inspection Act of 1906, the Poultry Products Inspection Act of 1957 and the Egg Products Inspection Act of 1970. The FSIS also acts as a national health department and is responsible for the safety of public food-related establishments as well as business investigation.