Figure clearly distinguishes between three groups of EOM-CC methods: one in which the principal character of target states is described by annihilation operators (EOM-IP, EOM-DIP), one in which the principal character is described by creation operators (EOM-EA, EOM-DEA), and one in which the principal character is described by both creation and annihilation operators (EOM-EE, EOM-SF, EOM-DSF). For the first group of methods, FNOs derived from the reference state density matrix should provide a reasonable recipe for the virtual space truncation, since the virtual space is primarily responsible for describing correlation of the target states. However, for the second group, truncation of the virtual space affects the description of the leading configurations of the target states, thus suggesting that the FNOs derived from the reference-state density matrix may not provide an optimal and balanced truncation scheme. The methods from the third group present an interesting case. Whereas the quality of the EOM-EE states can be adversely affected by the virtual space truncation based on the ground state correlation (as in the hypothetical example of Rydberg and valence states discussed above), the quality of the EOM-SF states should not be compromised by the virtual space truncation based on the reference-state correlation because the virtual orbitals needed to describe the target spin-flip states should have the same character as the occupied orbitals hosting the unpaired electrons in the high-spin reference.