The quest for realistic mathematical representations of molecular potentials goes back to the origins of theoretical chemistry 100 years ago, when the Lennard-Jones (LJ) potential was reported in 1931. For a history of empirical potentials for use in condensed phase simulations see ref. 2. For chemical reactions the historically important London-Eyring-Polanyi-Sato potential for three atoms is the landmark. The LJ potential is still widely used and the LEPS potentials have been extended to tetratomic reactions 5 using important 3-body and 4-body terms. Such potentials were used until the mid-2000s. Since then, there have been major advances in this quest, especially for molecules and chemical reactions. This was made by overcoming the condrundrum that bedeviled the advance to larger molecules. This was what we might term the "3N -6 orthodoxy" that was discussed in detail in our 2018 review. In brief it was the accepted "fact" that the PES should be functions of the 3N -6 vibrational degrees of freedom. So expressing a potential in terms of all internuclear distances would violate this fact if N exceeds four. For molecules larger than tetraatomics the 3N -6 variables would typically be bond lengths, bond angles and dihedral angles. An example of using these variables for the 6-atom reaction H+CH 4 can be found in ref . 11. This orthodoxy was upended, to the best of our knowledge, in 2003 when the first potential for CH was reported using all 15 internuclear distances. This usage was in fact necessary for the first implementation of permutationally invariant polynomials to represent a potential energy surface. More discussion of this can be found in reviews of the PIP approach, Subsequently, descriptors for global representations of Machine Learned Potentials (MLPs) use all internuclear distances or transformed version thereof, such a Morse variables; these are described in more detail below. The current usage of all internuclear (or Morse) variables is now so widespread that this early condundrum is rarely mentioned in the literature. In short, using the set of "redundant" internuclear distances is a non-issue, provided one transforms from cartesian coordinates to internuclear distances as is always done currently.