The Office of Personnel Management (OPM) is responsible for creating and maintaining the structure of occupations and systems for classification of all Federal government positions. Classification is based on two fundamental principles:
1. Substantially equal pay for substantially equal work; and
2. Variations in pay in proportion to substantial differences in difficulty, responsibility, and qualifications required.
Classification consists of the position title, pay plan or pay schedule, occupational series, and grade or pay band level. These decisions, made by Human Resources Specialists or by managers, are based on nature and variety of the work, difficulty of the work, authority and responsibility exercised, extent of supervisor controls over the work, and qualifications.