This is what i could find:
CNC film classification:

Quote:
Decisions on cinematographic works (including trailers) made by the Minister after a recommendation from the Board involve the following measures :
certificate authorising the screening of the film to all members of the public
certificate prohibiting the screening of the film to minors under twelve
certificate prohibiting the screening of the film to minors under sixteen
certificate prohibiting the screening of the film to minors under eighteen
certificate totally prohibiting the screening of the film.


Films may also be classified by the order of the Minister of Culture as "pornographic films or those containing an incitement to violence" (article 12 of the act of 30 December 1975).

As from 1 January 1976, the list of pornographic films and those containing an incitement to violence is drawn up on the recommendation of the Board of Film Classification.
These films are not permitted to benefit from any financial support in the form of automatic selective aid.

And in the DVD rating there is another rating that is "Accord Parental" doesn't correspond to any rating in DVD Profiler. I have asked in the past to Ken if it's possible to add this rating between U ("Tous publics") and 12 but it seems it's too complicate so we won't have this rating in DVD Profiler.
So me I put NC when it's "Accord Parental" but some people put the U rating for "Accord Parental". But personally I think it's not exact because to my mind some DVDs with "Accord Parental" aren't good for kids particularly little kids...

Quoting Martin_Zuidervliet:

Quote:
I do not know much about the French Rating System, but this is what I do know:

These are the ratings according to Wikipedia
These are the ratings according to a French user

And if he's right (and I think he is), the ratings indeed need to be adjusted for DVD Profiler.

I think in fact the rating from Wikipedia is for the theater. And the rating for DVD is a little bit more different... Why? I don't know.
I don't know how it's work for the X movies and I didn't view for the moment a DVD not X with a rating of "Interdit aux moins de 18 ans" so I don't know if in the reality there is a distinction between a DVD with a rating of 18 and with a DVD X also forbidden to people of less 18 years old.
So for the DVD rating that is what is helpful for DVD Profiler we have:
  - "Tous publics" that correspond to U in DVD Profiler
  - "Accord Parental' without any corresponding in DVD Profiler
  - "Interdit aux moins de 12 ans" that correspond to 12 in DVD Profiler
  - "Interdit aux moins de 16 ans" that correspond to 16 in DVD Profiler
  - ?? that correspond to Adult in DVD Profiler

So if it exist a rating "Interdit aux moins de 18 ans" there is no rating in DVD Profiler for that. So I don't know if there are DVD with this rating and that are not DVD X. If yes we need to have a new rating in DVD Profiler. And to be complety accurate we need to have a rating for "Accord Parental' but Ken didn't want because we need to modify all the actual 12 profiles that will automatically change by "Accord Parental" but I don't why it will be changed in the database of DVD Profiler if we add a rating between U and 12...

Quoting goodguy:

Quote:
Please see also this thread about DVDProfiler's implementation of ratings.

I already submitted a link to your thread.

Quoting surfeur51:

Quote:

In dvdprofiler, we have :
NC, with no use, as all movies are rated.
U, 12 and 16, which are correct,
adult, which means nothing as it doesn't make the difference between 18 and X

I have a lot of DVD of France without any rating, specially spectacle or manga, anime, ... but it's false to say all movies are rated... movies maybe but not all DVD!

I'm from Quebec

Here we have
G    for Suitable for viewers of all ages (General)
PG  for Parental guidance is advised.  Theme or content may not be suitable for all children (Parental
      Guidance)
14a for Suitable for viewing by persons 14 years of age and older.  Persons under 14 must be
      accompanied by an adult.  May contain: violence, coarse language and/or sexually suggestive
      scenes.
18a for Suitable for viewing by persons 18 years of age and older.  Persons under 18 may attend but
      must be accompanied by an adult.  May contain:  explicit violence, frequent coarse language,
      sexual activity and/or horror.
R    for Admittance restricted to persons 18 years of age and over.  Content not suitable for minors.
    May contain:  frequent use of sexual activity, brutal/graphic violence, intense horror and/or other
    disturbing content.
NC  for film that not fit any of the others.
Adult (Only for porn or sex oriented movies)

You might also look at
http://freebase.com/view/film/content_rating_system

for other country rating systems