Further refinements to the aerodynamic profile yielded little improvement. The second prototype, S-2, introduced some aerodynamic refinements. Many refinements and variations have been added to the basic template. The number of Unified Process refinements and variations are countless. The entire surface was now flush riveted and the aircraft had several other aerodynamic refinements. Practical implications and recommendations for future refinements of ASJT are discussed. New refinements appeared on the 1965 redesign. After refinements and engineering considerations being made, the final design specifications were frozen in 2006. N-1/U was fitted with MG 151/20 and unspecified aerodynamic refinements. The following is a list of some of the better known refinements and variations. Later, gas and diesel engines appeared with other refinements and specifications. Hopefully two possible refinements of Generalized Paxos are possible to improve recovery time. It experimented with pressurized cabins and other technical refinements. It featured additional story elements, gameplay refinements and a new difficulty setting. Decoherence is an important part of some modern refinements of the Copenhagen interpretation.