orthonym.assembly.chain_prefix_positions

Note

Internal API. Names and behaviour may change between releases.

The substituent positions that the prefixes of a chain parent cite.

The locant of a lone substituent on ethane is omitted (b), the Blue Book, ‘ethanol’). Citation of locants (:2869) cites all locants of a unit when any is essential, so a second prefix on the same chain makes the locant of the first essential. The prefixes of a chain come from more than one writer (the branch namer, the functional-group prefix loop, the ring-prefix generator), and the branch namer sees only its own.

orthonym.assembly.chain_prefix_positions.chain_prefix_positions(features, branch_namer_positions)

The number of substituent branches on the principal chain of features, at least the branch_namer_positions the branch namer itself cites. features.substituents holds every branch of the chain by its locant, whoever writes its prefix.