A theory of explanation might treat explanations in either a realist or an epistemic (that is, anti-realist) sense. A realist interpretation of explanation holds that the entities or processes an explanation posits actually exist--the explanation is a literal description of external reality.
Officers in pay grades O-1, O-2, and O-3 with more than four years of prior cumulative service in an enlisted or warrant officer grade are paid increased wages using the special pay grades of O-1E, O-2E, and O-3E, respectively.
There are many other types of pay structures and salary structures e.g. pay spines, benefit structures, spot rates, fixed rate, time rate. All of these pay structures will be looked at in more detail in the next chapter. (I) PAY RANGES. Each grade or band has a pay range or scale with a minimum and a maximum.