The situation becomes more complex when the form of energy does not remain constant. In this context Ohta formulated the question of energy quality in terms of the conversion of energy of one form into another, that is the transformation of energy. Here, energy quality is defined by the relative ease with which the energy transforms, from form to form.
Nomenclature: Prior to Ohtas definition above, A. W. Culp produced an energy conversion table describing the different conversions from one energy to another. Culps treatment made use of a subscript to indicate which energy form is being talked about. Therefore, instead of writing "energy A", like Ohta above, Culp referred to "J", to specify electrical form of energy, where "J" refers to "energy", and the "e" subscript refers to electrical form of energy. Culps notation anticipated Sciencemans (1997) later maxim that all energy should be specified as form energy with the appropriate subscript.