m_F322W2 vs. m_F606W − m_F322W2 CMD of Boötes I, where the gray shaded area indicates the region used to study binaries and derive the binary map. The nine green lines delimit the eight subregions (R1 − R8) adopted for the binary analysis. The bluest line represents the fiducial sequence of single stars, shifted to the blue to encompass the bulk of MS stars, while the reddest line corresponds to the fiducial of equal-mass binaries, shifted to the red to include most binaries. The remaining lines represent fiducial sequences of binaries with mass ratios ranging from 0.3 to 1.0, as indicated.