The Master Address Repository (MAR) will serve as the source repository for addressing information in the District. The MAR will provide District agencies with an authoritative single source for accurate address data within the District of Columbia. Each address contained in the Master Address Repository will be linked to a specific geographic feature that is contained within the DC GIS. The MAR will provide the capability to agencies to match their address information against it for validation and verification. The toolset accompanying the MAR will output xy coordinates for verified addresses as well as a list of addresses requiring more research.

Agencies are encouraged to adhere to the following guidelines when creating or appending geospatial by geocoding addresses:

• Use the MAR (point geocoding against address points) as the primary method for geocoding.
• If the above method fails, use the MAR to validate individual address components (street name, quad, zip code, etc) and rerun.
• Use interpolation between address points as the secondary method of geocoding .
• Use street centerlines address ranges as the tertiary method of geocoding.
• Note in the record which of the above methods was used to geocode each point.
• If geocoding against the MAR was successful, store the AID (address identification number) returned by the MAR in your local database.
• If the MAR fails or returns suspect results, report them to DC GIS.