D.C. Mun. Regs. tit. 19, § 2312
2312.1 The length of a round in a contest is two (2) minutes, and there is a one (1) minute rest between rounds.
2312.2 A professional contest shall be scheduled for a minimum of five (5) rounds.
2312.3 An amateur contest may not exceed five (5) rounds.
SOURCE: Final Rulemaking at 35 DCR 3759, 3763 (May 20, 1988).