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.
Wage grade is the term used for workers with recognizable skills. These are the people responsible for operation and maintenance of government business entities. The salary is based on similar jobs in the immediate area and the pay grade has 5 steps. There is little lateral movement and promotions are also limited.