William Rotsler, who wrote "The XXX-rating means hard-core, the XX-rating is for simulation, and an X-rating is for comparatively cool films." Nothing beyond the simple X rating has ever been officially recognized by the MPAA.
Because of the heavy use of the X rating by pornographers, it became associated largely with pornographic films, so that non-pornographic films given an X rating would have fewer theaters willing to book them and fewer venues for advertising.
In response, the MPAA eventually agreed in 1990 to a new NC-17 rating that would be trademarked, and could only be applied by the MPAA itself.
The exhibition or sale of these films to people under the age of 18 years is a criminal offence carrying a maximum fine of ,500.
The Battleship Potemkin was rejected for "inflammatory subtitles and Bolshevik propaganda" in 1926, rated X in 1954, and finally rated PG in 1987.