Our goal is therefore to minimize MSE of the reduced Gibbs free energy surface of the trial model parameters from the IAPW95 experimental data, while setting maximal deviations for the MSE for all simulated physical property surfaces in the form of constraint equations. No weights are required in the objective main function, as we are optimizing only using reduced free energies, which obviously are all comparable. However, we have significant choices remaining in the magnitude of the constraints, or equivalently, the weights on the constraints, as shown in parts 1-5 of eq. 2. Because we are parameterizing a complex free energy surface with a 6 parameter energy function that does not contain the entire physics, there will be deviations of different properties. Any such choice of constraint magnitudes depends on the user-defined objectives, goals and desired outcomes.