D.C. Mun. Regs. tit. 19, r. 19-2326
The timekeeper shall sit at ringside closest to the gong. The timekeeper shall indicate the beginning and end of each round by striking the gong once with a metal hammer.
The timekeeper have a whistle and an accurate stopwatch that an inspector of the Commission has examined and certified.
The timekeeper shall warn the seconds of the contestants by blowing a whistle ten (10) seconds before the beginning of each round.
A knockdown timekeeper shall assist the timekeeper. As soon as a contestant is knocked down, the knockdown timekeeper shall strike the floor of the ring with a hammer or mallet at one (1) second intervals as long as the contestant is down on the floor. This count may continue beyond ten (10) since the referee may encounter difficulty keeping the contestant scoring the knockdown in the farthest corner. In this case the knockdown timekeeper shall continue to strike the floor, and the referee, upon resuming the count, shall pick up the count with the beat of the timekeeper's hammer or mallet.
D.C. Mun. Regs. tit. 19, r. 19-2326