Compounds having the structure RON=C:. So called because fulminic acid (actually HC≡N+–O− formonitrile oxide) was previously considered to be HON=C:.
Salts of fulminic acid, e.g. Na+[–C≡N+O−].
Source: PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1336 (https://doi.org/10.1351/pac199567081307)