(U-B)0, (B-V)0 diagram for stars of luminosity class V with the solar chemical composition

A true-color line, i.e., a (U-B)0, (U-B)0(K) diagram, is constructed for O5-K5 stars of luminosity class V with the solar chemical composition (Fe/H = 0). Through a comparison with the corresponding diagram for stars of luminosity class V obtained by Straizys, it is established that for O5 V-K3 stars the difference in color indices is /Delta (B-V)0/ = /(B-V)0(K) - (B-V)0(1)/ less than 0.003 m, i.e., the two (B-V)0 systems practically coincide.