D.C. Mun. Regs. tit. 11, § 2904
2904.1 For the purposes of the USN District, each Platform and all improvements constructed thereon are deemed to comprise a single building.
2904.2 Any part of a single building that is not connected to any other part of the same single building, other than through the structure of the Platform, will be hereinafter referred to as a Building Unit.
SOURCE: Notice of Final Rulemaking published at 58 DCR 4788, 4795 (June 3, 2011).