The discussion of the kinetic energy balance given in the previous sections allows for a partitioning of the terms determining the kinetic energy evolution into various physical processes. In MOM, it is also useful to determine such budgets for certain physical and numerical reasons. For example, by computing separately both sides to the various kinetic energy budgets, it is possible to determine the consistency of the various discretizations of physical processes. This calculation is provided by the diagnostic option energy_analysis (Section 39.4). This diagnostic has proven an indispensible tool in formulating various new algorithms in MOM. The following discussion provides the basic approach used to determine the internal and external mode energy budgets as implemented in option energy_analysis. Note that some of the manipulations presented in earlier sections can be generalized quite simply to those required for this section. However, for the sake of completeness, the manipulations are presented here in their fundamental form.