This tag should be added to French bouillon restaurants, which offer traditional dishes from French (or even Parisian) cuisine and the bistro tradition (boeuf bourguignon, oeufs mayo, croque-monsieur, etc.) at affordable prices. The term " bouillon " is usually included in the restaurant's name.
Also specify, adding the necessary tag, if the restaurant offers : frogs' legs, snails, oysters, caviar, foie gras, pâté en croûte, mayo eggs, croque-monsieur, onion soup, moules-frites, steak-frites, steak tartare, coq au vin, confit et magret de canard, game, boeuf bourguignon, blanquette, choucroute, quiche lorraine, cassoulet, raclette, tartiflette, fondue, galette bretonne, crêpe, crêpes Suzette.