Ключевые слова: 21, 3d, adult, age, alert, attention, caution, cigarette, circle, computer, content, eighteen, erotic, forbid, horror, illegal, illustration, info, internet, label, law, letters, limited, movie, no, number, old, over, person, plus, politics, prohibition, protection, rating, recommendation, red, restricted, sex, sexual, sexuality, sign, signal, stop, symbol, under, warning, web, white, young,