Park Model RVs are created as a new membership category. Below is a direct quote from their website.
On July 1, 2012, RVIA created a new membership category for manufacturers of park model RVs (PMRVs). A park model RV (also known as a recreational park trailer) is a trailer-type RV that is designed to provide temporary accommodation for recreation, camping or seasonal use. PMRVs are built on a single chassis, mounted on wheels and have a gross trailer area not exceeding 400 square feet in the set -up mode. They are certified by their manufacturers as complying with the ANSI A119.5 standard for recreational park trailers.
PMRVs are most often used in recreational vehicle campgrounds. They may be owned by the campground and rented to guests, or they may be brought in and used exclusively by their owners on a site rented or leased from the campground. These RVs are used for recreational purposes only. They are not meant to be permanently affixed to the property, they do not improve property values in any way, and they are neither designed nor intended by their manufacturers to be used as permanent residences.
Two different types of park model RVs are offered. One type is less than 8′ 6″ in width and is designed for frequent travel on the highways while the other and more popular type is wider than 8′ 6″ (usually 12′ in width), and must be transported with special movement permit. The 8′ 6″ unit typically is expandable when it reaches its destination utilizing slide-outs or tip-outs. The wider units, being less mobile, are usually sited in a resort or RV park location for an extended term, typically several years. Park model RVs are titled as vehicles by the various states. This is because PMRVs are built on permanent chassis such that they can be and are moved either within a campground or between campgrounds.
Most park model RV owners (67%) locate their unit within several hours of drive time from their primary residences and use them for weekend camping get-aways. Some owners may place their units in a warm climate location and use their PMRVs as a seasonal/temporary get-away in the winter, while others place their PMRVs in cooler climate locations to escape the summer heat and humidity back home.
The Recreation Vehicle Industry Association (RVIA) operates a safety standards and inspection program that requires member manufacturers of recreation vehicles to affix an RVIA standards program seal to every unit they build in their factories. This seal indicates the manufacturer’s certification that the RV complies with the requirements of all applicable standards. A recreational park trailer can always be identified by the blue and gold RVIA ANSI A119.5 certification seal (or its predecessor green RPTIA seal) affixed adjacent to the main door of the unit.
They have additional information and PDFs you can download and view from their website.