HR1 vs. HR2, where HR1 = ( H1 − S2 − S1)/( H1 + S2 + S1) and HR2 = ( H2 − H1)/( H2 + H1). The blue and red symbols are the same representation of GC-LMXBs as in Figure 4(a), whereas black crosses represent those field X-ray sources detected within R = 4′ and simultaneously detected in the F, M, and H2 bands. For clarity, error bars are not shown for the field sources, which have a similar uncertainty range as those of the GC-LMXBs.