Kiel-diagrams for stars with [Fe/H] = −2 (top), −0.5 (middle), 0.0 (bottom), and the three different WEAVE HR set-ups (blue: left, green: middle, and red: right). The colour code represents the number of lines associated with α-elements (O, Mg, Si, S, Ca, Ti) having a purity greater than 0.8 and detectable for a S/N_resoļ < 70. The size of the points is proportional to the number of α-elements with useful lines at a given combination of T_eff, log g, and [M/H], As a reference, the size of a point for which four elements would have been detected is plotted as a black solid circle at the position of the Kiel diagram, for which we have templates.