OP year
(11) Original production (OP) year. The calendar year in which the motor vehicle or motor vehicle engine was originally produced by the OEM. (12) Original production (OP) years old. The age of a vehicle as determined by subtracting the original production year of the vehicle from the calendar year of importation. (13) Running changes. Those changes in vehicle or engine configuration, equipment or calibration which are made by an OEM or ICI in the course of motor vehicle or motor vehicle engine production. (14) United States. United States includes the States, the District of Columbia, the Commonwealth of Puerto Rico, the Commonwealth of the Northern Mariana Islands, Guam, American Samoa, and the U.S. Virgin Islands. (15) Useful life. A period of time/mileage as specified in part 86 for a nonconforming vehicle which begins at the time of resale (for a motor vehicle or motor vehicle engine owned by the ICI at the time of importation) or release to the owner (for a motor vehicle or motor vehicle engine not owned by the ICI at the time of importation) of the motor vehicle or motor vehicle engine by the ICI after modification and/or test pursuant to 85.1505 or 85.1509. (16) Working day. Any day on which Federal government offices are open for normal business. Saturdays, Sundays, and official Federal holidays are not working days.