Etiquette for ID of species with no visual differences

@bouteloua is there any place I can read some documentation about Holding bins and the associated workflow (creation, use etc)?
I found just this https://forum.inaturalist.org/t/observation-field-standardization-wiki/380 but the description does not seem to fit the use I read in the links I posted here.
Was that an experiment? Is it running or obsolete?
Asking since I’m considering switching to the Holding bin+comment on genus id (the nasty one)+not improvable flag approach but of course this must be supported by curators.