
The ultimate arbiter is the USDA's 2003 publication: Food Standards and Labelling Policy Book, which says:
PRIME RIB OF BEEF OR STANDING BEEF RIB ROAST FOR PRIME RIB:
These products do not have to be derived from USDA prime grade beef.
I have a problem with that. By this definition, technically a rib roast from a Commercial or Utility Grade hunk of beef could be sold as prime rib. Now, in the interest of honesty, I must say that Prime Rib is not something I crave. Take the same cut of meat and cut it into thick, bone-in steaks to toss on the grill and I am fine. Roast it whole and it tastes like a hunk of boogers. But like Prime Rib of beef or not, the concept of a "prime rib" of pork just doesn't exist except in the pin heads of the pinheads of some marketing department. It may be the rib section of some piggy, but since the have bred the fat out of pork to create "the other white meat" you won't get
the mouthfeel of a Choice Standing Rib Roast, let alone a Prime Cut.
The problem is that consumers are gullible. They'll think they are getting something special.
Just tell us what we are getting.
Rant Off!