D = The film is spoken in German.
E = The film is spoken in English.
F = The film is spoken in French.
CH-D = The film is spoken in Swiss German.
OV = The film is spoken in the original language. You can see which language this is in the film overview.
d = The film has German subtitles.
e = The film has English subtitles.
f = The film has French subtitles.
If it has several small letters, e.g. d/f, it means that the film has subtitles in several languages, which are displayed one below the other.