Top panel: objects that satisfy the modified (Lindegren et al. 2018) criteria (gray points) with those with the stringent halo criteria and the crowded region criterion applied (small light blue dots). Xue et al. (2008) objects (red circles) and Behr (2003) objects (yellow triangles) are superimposed. The green trapezium denotes the Gaia DR2 colour-magnitude coordinate space (final CMD criteria) considered as the (blue horizontal-branch region) displayed in DR2 (upper panel) and EDR3 (lower panel).