1.Compounds having the structure RON=C:, so called because fulminic acid (actually HC≡N+–O− formonitrile oxide) was previously considered to be HON=C:. 2.Salts of fulminic acid, e.g. Na+[–C≡N+O−]., Fulmiinhappe soolad –[≡N+O−]- ja ühendid struktuuriga HC≡N+–O−  (formonitriiloksiid ja selle derivaadid).