 Complete the following phrase:  In 1976, the USAF issued a requirement for a new generation, dubbed Paveway III, that finally entered service in 1986. The Paveway III system used a much more sophisticated seeker with a wider field of view and proportional guidance, minimizing the energy loss of course corrections. Paveway III has a considerably longer glide range and greater accuracy than Paveway II, but it is substantially more expensive, limiting its use to high-value targets. Although Paveway III kits were developed for the smaller Mk 82 weapons, limited effectiveness caused the USAF to adopt the kit only for the larger 907 kg 2,000 lb class weapons the Mk 84 and BLU-109. Paveway III guidance kits were also used on the GBU-28B penetration bomb fielded at the close of the 