Realtor associations created multiple listing services decades ago as marketplaces to help brokers representing sellers and brokers representing buyers cooperate. The vast majority of home sales in this country occur through MLSs. As marketplaces made up of cooperating competitors, MLSs are responsible for ensuring everybody follows the same rules, complies with the law and pays what they say they’re going to pay. In that vein, the National Association of Realtors imposes policies on Realtor-affiliated MLSs, which comprise the vast majority of the nation’s 800 or so MLSs. But MLSs aren’t just compliance cops. When real estate agents and brokers want to help clients buy or sell a home, their most important technology tool is generally the MLS. In May, NAR announced a partn…