Similar to Fig. 2 but for the bMS stars. (a) Preliminary selection of bMS stars on the m_F438W − m_F814W CMD (within the red lines). Already identified MSa1 and MSa2 stars have been removed from the CMD. (b)-(c) Preliminarily selected bMS stars are further refined using the m_F336W − m_F438W and m_F275W − m_F438W CMDs. As for Fig. 2, stars surviving from the previous panel are in black, while rejected stars are in grey. (d)-(f) Fiducial lines (in green) used to verticalise the MSa in the m_F336W − m_F438W and m_F275W − m_F336W CMDs. (e)-(g) Verticalised ${\mathrm{\Delta }}_{m_{F336W}-m_{F438W}}^{\text{N}}$ and ${\mathrm{\Delta }}_{m_{F336W}-m_{F438W}}^{\text{N}}$ CMDs. (h) ${\mathrm{\Delta }}_{m_{F336W}-m_{F438W}}^{\text{N}}$ versus ${\mathrm{\Delta }}_{m_{F275W}-m_{F814W}}^{\text{N}}$. (i) Hess diagram of the TpCD. (l) Three main subcomponents of the bMS, namely bMS1 (dark blue), bMS2 (azure), and bMS3 (light blue).