English: Different colors symbolize different types of atomic clocks:

Red<->Caesium Beam Green<->Caesium Fountain Gold<->Rubidium Fountain Optical<->Blue

Each row of dots represents an atomic clock, for example, NIST-F2 clock has a row of dots. The dots symbolize times and dates when the clock accuracy was evaluated for establishing International Atomic Time (TAI). The clocks with bigger rows of dots have been evaluated within a month of contributing to the TAI accuracy clock ensemble. The accuracy evaluation u_B reports of various primary frequency and time standards are published online by the International Bureau of Weights and Measures (BIPM) and are part of the Circular T '3 - Duration of the TAI scale interval d.' paragraph.^[1]