just the text
Basal State, on many webpages, is defined along the lines of my description above. For example, on coinauctionshelp.com Basal State is said to be when “you can tell it was a coin but not what type.” It appears, however, that unidentifiability is not an exhaustive definition. It’s easy to find coins of this grade being sold as particular kinds of coins, and they presumably have been reliably identified as such. So it seems that in practice a Basal State coin is one with extremely heavy wear, including cases where the level of wear prevents identification.