In 2003, Boeing Photographic Services documented the significant steps in the manufacturing and assembly of a Southwest Airlines' 737-700, also known as line unit 1369, as part an educational effort at Southwest Airlines to show employees how an airplane is built. Southwest Airlines, an exclusive operator of 737 airplanes, posted the images and accompanying descriptive text on its internal Web site. The documentation, which included photos of the airplane’s nacelles and struts, continued as the airframe progressed through final assembly at the Renton factory. Southwest Airlines was the launch customer for members of the Next-Generation 737 family.