Classification of BHB stars based on their positions on the Kiel diagram. The magenta dashed line marks the boundary distinguishing redder BHB stars and bluer BHB stars in the plane of effective temperature and surface gravity. The gray dots represent halo-like BHB stars, while the black dots denote disk-like BHB stars. Halo-like observed binaries (red stars) and disk-like observed binaries (cyan stars) are highlighted accordingly.