[α/Fe] versus [Fe/H] for the Adibekyan et al. (2012) sample, where open circles, open squares, and asterisks represent stars with P_thin ≥ 0.90, P_thick ≥ 0.90, and P_halo ≥ 0.90 (from Bensby et al. 2003), respectively. Filled circles and squares show the stars within the Soubiran & Girard (2005) sample with P_thin ≥ 0.90 and P_thick ≥ 0.90 (from Mishenina et al. 2004), respectively. The positions of the two targets XO-2N and XO-2S are displayed with large yellow and green five-pointed star symbols, respectively.