# 532.501 Definitions.
In this subpart:
*Administrative workweek* means a period of seven consecutive calendar days.
*Basic workweek* for full time employees means the days and hours within an administrative workweek which make up the employee's regularly scheduled 40-hour workweek.
*Environmental differential* means a differential paid for a duty involving unusually severe hazards or working conditions.
*Irregular or occasional overtime work* means overtime work which is not part of the regularly scheduled administrative workweek.
*Night shift differential* means the differential paid the employee when the majority of regularly scheduled nonovertime hours worked fall between 3 p.m. and 8 a.m.
*Overtime work* means authorized and approved hours of work performed by an employee in excess of eight hours in a day or in excess of 40 hours in an administrative workweek, and includes irregular or occasional overtime work and regular overtime work.
*Premium pay* means additional compensation for overtime, or Sunday work, and standby duty.
*Sunday work* means work performed during a regularly scheduled tour of duty within a basic workweek when any part of that work which is not overtime work is performed on Sunday.
*Regular overtime work* means overtime work which is a part of the regularly scheduled administrative workweek.
*Regularly scheduled administrative workweek* means:
(1) For full-time employees, the period within an administrative workweek within which employees are scheduled to be on duty regularly.
(2) For part-time employees, it means the days and hours within an administrative workweek during which these employees are scheduled to be on duty regularly.
*Tour of duty* means the hours of a day, *i.e.,* a daily tour of duty, and the days of an administrative workweek, *i.e.,* a weekly tour of duty, that are scheduled in advance and during which an employee is required to perform on a regularly recurring basis.