NAR Policy Statement 7.90
Policy Statement 7.90 of the National Association of REALTORS' Multiple Listing Service policy requires association-owned MLSs to certify against the RESO Data Dictionary and RESO Web API within one year of each version's ratification. It is not legislation and no regulator enforces it; compliance is a condition of NAR affiliation. It is the only industry-imposed machine-readable API mandate identified across the API Evangelist sector series.
Regions
Industries
Each links to that industry as a scored cohort — so the question "how ready is this sector for the regime that governs it?" becomes one you can actually look at.
Implemented by these standards
A regulation is the law; a standard is the machine-readable contract that satisfies it. Almost every regime in this catalog restricts an interface rather than requiring one — where a standard exists, it is the part a provider can actually publish.