Traditionally, most National Guard personnel serve "One weekend a month, two weeks a year", although personnel in highly operational or high demand units serve far more frequently. Typical examples are pilots, navigators and aircrewmen in active flying assignments, primarily in the Air National Guard, and to a lesser extent in the Army National Guard, and special operations airmen and soldiers in both. A significant number also serve in a full-time capacity in roles such as Active Guard and Reserve (AGR) or Air Reserve Technician or Army Reserve Technician (ART).