Reference sets for HR15N and HR10|HR21 setups. Top row: Kiel diagrams for full HR15N sample, final HR15N reference set and WG11 cross-match with HR15N. Second row: same as for the top row but for [Fe/H] versus T_eff. Third row: Kiel diagrams of the four main samples: benchmarks (yellow), OC (magenta), GCs (green), and MW (blue) within the HR15N reference set overlaid on the full reference set. Fourth row: same as for the third row but for [Fe/H] versus T_eff. Fifth to eighth rows: same but for HR10|HR21.