Rings having (formally) the maximum number of noncumulative double bonds, e.g. benzene,
indene, indole, 4
H-1,3-dioxine. Also called mancunide-ring systems.
Source:
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on
structure (IUPAC Recommendations 1995))
on page 1348