A mock entry plug developed in order to activate and operate the Evangelion without the pilots. Although the personal pattern of the Children is transplanted to the plug, digitisation of the soul is impossible, so the dummy plug merely simulates thought patterns. The dummy plugs prepared by NERV used the personal pattern of the First Children, Rei Ayanami, whereas the dummy plugs prepared by SEELE used the personal pattern of the Fifth Children, Kaoru Nagisa.

Source: The End of Evangelion : Glossary contained within The End of Evangelion - Theatrical Program.