PRT

PRT might refer to
 * PRT (CADKEY) - became KeyCreator
 * PRT (PTC) - Pro/Engineer, Pro/E Wildfire, Creo Parametric
 * PRT (UG) - Unigraphics, Siemens PLM, NX CAD
 * SLDPRT - SolidWorks 3D part model (had .prt extension earlier)