Realtors Property Resource LLC has signed an agreement with the nation's largest multiple listing service -- Rockville, Md.-based Metropolitan Regional Information Systems Inc. -- plugging a gap in the national property database's listings coverage on the Eastern seaboard.MRIS' coverage area encompasses four dozen counties in Maryland and Virginia, and includes Washington, D.C., Baltimore, and surrounding communities. Last year, the MLS handled 219,000 listings and 108,000 sales, and its 40,000 subscribers currently represent more than 70,000 listings, including 52,000 residential properties.A National Association of Realtors subsidiary, RPR is partnering with Lender Processing Services, MLSs, and other data providers to provide tax assessment and public property records; records on mort...