The AAP DTD has been succeeded by ISO 12083[?].
This article (or an earlier version of it) contains material from FOLDOC, used with permission.
... Republics (USSR) Cheka (1917-1922) Gosudarstvennoye Politicseskoye Upravleniye[?] (GPU, 1922-1923) Obyedinennoye Gosudarstvennoye Politicheskoye Upravleniye[?] ...