For the purposes of this Charter a “regional or minority languages” means languages that are: traditionally used within a given territory of a State by nationals of that State who form a group numerically smaller than the rest of the State’s population; and different from the official language(s) of that State; it does not include either dialects of the official language(s) of the State or the languages of migrants; “territory in which the regional or minority language is used” means the geographical area in which the said language is the mode of expression of a number of people justifying the adoption of the various protective and promotional measures provided for in this Charter; “non-territorial languages” means languages used by nationals of the State which differ from the language or languages used by the rest of the State’s population but which, although traditionally used within the territory of the State, cannot be identified with a particular area thereof.
ETS 148 – Regional or Minority Languages, 5.XI.1992 LINK