Table : Mean absolute deviations (MADs) and standard deviations (SDs) in kJ • mol -1 for reaction energies and barrier heights of the proton transfer reactions from the BH9 set with respect to TIGHTPNO DLPNO-CCSD(T 0 ). Pair-selected multi-level DLPNO-CCSD(T 0 ) with TIGHTPNO and NORMALPNO as target accuracies is compared to NORMALPNO DLPNO-CCSD(T 0 ) for the aug-cc-pVTZ and aug-cc-pVQZ basis sets. For the latter, the errors are additionally decomposed into DLPNO-CCSD and DLPNO-(T 0 ) with respect to TIGHTPNO DLPNO-CCSD and TIGHTPNO DLPNO-(T 0 ), respectively.