D.C. Code § 47-704

For the purpose of facilitating the assessment and taxation of real property in the territory within the limits of the District of Columbia lying outside of the City of Washington the following system of designating the several subdivisions, blocks, lots, and parcels of land is hereby prescribed, and each and every designation made or given in conformity with said system shall be deemed a sufficient description of the property to which it relates for all purposes of assessment and the collection of taxes and assessments of every kind.