The purpose of this standard is to provide, for mechanical transport refrigeration units employing forced-circulation air-coolers: definitions; testing requirements; rating requirements; performance requirements; unit marking and conformance conditions. This standard applies to mechanical transport compression type transport refrigeration units with; a prime mover as described in unit manufacturer's literature (speed-governed units only); coupling, transmission or V-belt drive-compressor to prime mover (if required); and a power train (coupling, power take-off or transmission, or V-belt drive) connecting the unit to the prime mover (variable speed units only). May be supplied either by manufacturer or by customer to manufacturer's specifications.