Obviously it helps that we've got standards. E.g. a restaurant can shop for "boneless pork loin roasts", and they have some idea of what they are getting. It isn't OK to call a trotter (pig foot) a pork chop. It helps that there is an official definition of what a pork chop is, and what a trotter is.
The federal governments FMIS (part of USDA) regulates the labeling of meat, under the FMIA and other laws. As food labeling is an important and complicated issue, they provide a "comprehensive, user-friendly document on the basic food labeling requirements for meat and poultry products" to help everyone. As it explains, mislabeling a product can have huge consequences:
The NAMP "Meat Buyers Guide" is one specification of pork cuts. You typically see things quoted with NAMP codes - like NAMP 412A for "center-cut pork loin roast".
If a product is deemed misbranded, its manufacturer faces a wide range of penalties that can be imposed by FSIS. These include withholding (rescinding) the use of labeling; product retention (prohibiting shipment); product detention (prohibiting sale from anywhere in the chain of commerce); request for product recall, press releases, and/or fines; and criminal prosecution. In addition, the facility producing misbranded product faces the possibility of inspection suspension or withdrawal.
Another set of specifications is from the USDA's AMS (Agricultural Marketing Service). They've got their IMPS (INSTITUTIONAL MEAT PURCHASE SPECIFICATIONS) documents. For pork, fresh pork (series 400), says, for example, that item 413A is a "pork loin, roast, boneless", defining it from item 413, which is defined from item 410, which says:
Until very recently, I had no idea of how complicated and legalistic all this is.
Item No. 410 - Pork Loin - The loin is that portion of the side remaining after removal of the shoulder, leg, belly, and fat back leaving a portion of the blade bone, its overlying lean and fat, not less than two (2) sacral, but no caudal vertebrae on the loin. The shoulder and leg shall be separated from the loin by straight cuts that are reasonably perpendicular to the split surface of the backbone. The outer tip of subscapularis muscle shall not extend past the center of the base of the medial ridge of the blade bone. The belly side shall be removed by a straight cut (a slight dorsal curvature is acceptable) which extends from a point which is ventral to but not more than 3.0 inches (7.5 cm) from the longissimus on the shoulder end, to a point on the leg end ventral to but not more than 1/2 inch (13 mm) from the tenderloin. Surface fat shall be trimmed to an average of 1/4 inch (6 mm) in depth or less except in the hip bone area. The hip bone area is defined as the area contained within two (2) parallel lines, 2.0 inches (5.0 cm) on either side of the anterior end of the hip bone and associated cartilage. Fat in the hipbone area shall be trimmed to the same contour as the rest of the trimmed fat surface of the loin. At least 2.0 inches (5.0 cm) of the false lean shall be exposed. Lumbar and pelvic fat shall be trimmed to 1/2 inch (13 mm) or less in depth. The tenderloin shall remain intact. The diaphragm and hanging tender shall be removed. The spinal cord groove shall be evident on at least 75 percent of the vertebrae.