Close Encounter is a term invented by J. Allen Hynek to justify his position in Blue Book, that was endorsed by the United States Air Force. Hynek devised a six-fold classification for UFO encounters arranged by increasing proximity. The terminology and system of classification was given in Hynek's 1972 book, The UFO Experience: A Scientific Inquiry.
The six-fold classification system that US intelligence groups had used, categorized persons of interest by who they thought were an increased risk to national security. The classification system is a form of profiling.
Internment Centers, established during World War II, were reopened in the 1950s in order to relocate persons of interest. The facilities were used to prevent Close Encounter cases from going public, keeping them in fully furnished imprisonment colonies.
- Men in Black