It is generally a part of the cellar, where friends meet, for a few drinks (wine), eat fondue or raclette, or simply salamis and other sausages.
If possible, eating fondue in the carnotzet is recommeded as cheese fondue leaves a smell less tempting than its taste, that can persist for a few hours.
This is why, in Switzerland, many restaurants park fondue eaters in a back room in order not to trouble the olfactive faculties of the gourmets in the main dining space.
Carnotzet in a cellarCarnotzet in a cellar
Carnotzet in a cellarCarnotzet in a cellar