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.
Here from USDA's Food Safety and Inspection Service (FSIS) is a glossary of meat and poultry labeling terms. FSIS is the agency responsible for ensuring the truthfulness and accuracy in labeling of meat and poultry products.