One way that Gregory reduced the number of unexplained UFOs was by simple reclassification. "Possible cases" became "probable", and "probable" cases were upgraded to certainties. By this logic, a "possible" comet became a "probable" comet, while a probable comet was flatly declared to have been a misidentified comet. Similarly, if a witness reported an observation of an unusual balloon-"like" object, Blue Book usually classified it as a balloon, with no research and qualification. These procedures became standard for most of Blue Book's later investigations; see Hynek's comments below.