The National Standard Plumbing Code (NSPC) is often called the New Jersey Plumbing Code. That is because New Jersey is the only state that adopts this code on a statewide basis. Other adoptions are by local jurisdictions in various states.
One of the unique aspects of the NSPC is that it is not published as a code. The only document available for purchase is the illustrated version of the code. There are illustrations throughout the code; however, the illustrations are technically not a part of the code since they are prepared independently of any code changes. There is language in the beginning of the code explaining that the illustrations are attempting to show one means of complying with the code.