Donald,

I think that in practice the potential taxon sensu Berendsohn (1995) is precisely what TDWG has primarily been addressing in recent discussion of taxon concepts.

I don't think so because AccordingTo is optional. We are in denger to have other than potential taxa. I don't see any reason that AccordingTo to be optional in TCS, because there must be a data source, i.e. the database itself, at least. Cheers, JMS