The "basic" thermochemical data set 110 consists of atomization energies (W4-11 data set), electron and proton affinities (G21EA and PA26 sets), ionization energies (G21IP and DIPCS10), bond dissociation energies (YBDE18 and AL2x6), and reaction energies (NBPRC, ALK8, G2RC, BH76RC, FH51, and TAUT15). Two other data sets, SEI4x4 and DC13, contain problems that are known to be particularly challenging for DFT. Error statistics are shown in Fig. , with MAEs for the individual data sets provided in Fig. and WTMAD2 values in Fig. .