Measurements of the EW of Ca ii for stars in the library of Cenarro et al. (2001). Circles are luminosity class III giants (open circles are stars whose spectral classification includes some chemical anomaly, while filled circles have no such qualifiers). Diamonds are luminosity class II bright giants. Triangles are supergiants (triangles pointing upwards have luminosity class Ib, while those pointing downwards have class Iab). With one single exception, giants and supergiants are well separated up to spectral type M2. The strongest Ca ii triplet corresponds to the K1 Ia–Iab supergiant HD 63302.