The Northern Italian languages are conventionally defined as those Romance languages spoken north of the La Spezia-Rimini Line, which runs through the northern Apennine Mountains just to the north of Tuscany; however, the dialects of Occitan and Franco-Provençal spoken in the extreme northwest of Italy (e.g. the Valdôtain in the Aosta Valley) are generally excluded. The classification of these languages is difficult and not agreed-upon, due both to the variations among the languages and to the fact that they share isoglosses of various sorts with both the Italo-Romance languages to the south and the Gallo-Romance languages to the northwest.