Caelum Incognitum — The interactive encyclopedia of ufology
Vallée classification
Classifications & scales
A classification system proposed by Jacques Vallée in Anatomy of a Phenomenon (1965) and refined later: anomalies (AN), fly-bys (FB), maneuvering discs (MD) and close encounters (CE), in numbered subtypes. More descriptive than Hynek’s, it aims at comparing cases statistically.