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.
Regulatory institutions and technologies of production have changed significantly since 1906 but, essentially, food safety laws have remained the same since then. For more than a hundred years, inspections have been the basis of the regulation of meat safety; still, regulatory enforcement by the FSIS has evolved.