(4.1.19) Carter : Regarding N-representability in contribution (4.1.17): This is more difficult than it seems -we worked on this for quite some time, without much success; see Chapter 7 of ref. 568. (4.1.20) Liu : Relevant to KEDFs in orbital-free DFT is the Pauli energy, which has recently been employed to identify strong covalent interactions. If approximate KEDFs are utilized for the same purpose, miserable results are obtained. This quality appraisal test for approximate KEDFs shows that they are unable to accurately account for the kinetic energy distribution in the medium range away from nuclei, where chemical bonding takes place and the Pauli energy plays a crucial role.