Chapter 10. Glossary of IRP Terms URS - Unified Registration System. The FMCSA now requires all new registration applicants to use the URS online registration application. All existing entities with a USDOT, MC, or FF number, or combinations of them will continue until such time as FMCSA publishes further regulation implementing the URS provisions. For more information about URS visit: www.fmcsa.dot.gov/registration/unified-registration-system USDOT Number - A number issued by the U.S. Department of Transportation, Federal Motor Carrier Safety Administration. apportioned vehicles. It is required by the RMV before you can renew or register 03/22http://www.fmcsa.dot.gov/registration/unified-registration-system