OB binaries with periods P ≤ 3 days across all morph parameter values (from 0 to 1), identified as MS systems from the OGLE sample (light grey dots) on the absolute color (M_V, max − M_I, max) – magnitude (M_V, max) space (where, the absolute magnitudes correspond to their values at maximum brightness of the binary). Overlaid are the empirically identified OGLE EW+ subsample from the LMC (yellow circles, as described in Section 2.2). Curves indicate the limits of the ZAMS and TAMS curves computed from non-rotating and rotating (v_i = 330 km/s) models of single stars with masses of 7 − 50 M_⊙.