This is an extension of the use of "epi-" in prefixes such as "epithio-". The prefix "endo-" has been used for the same purpose elsewhere (see IUPAC "Nomenclature of Fused and Bridged Fused
Ring Systems", Pure and Appl. Chem., in preparation).
This HTML reproduction is as close as possible to the published version [see IUPAC, Commission on Nomenclature of Organic Chemistry. A Guide to IUPAC Nomenclature of Organic Compounds
(Recommendations 1993), 1993, Blackwell Scientific publications, Copyright 1993 IUPAC]. If you need to cite these rules please quote this reference as their source.
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