I should have added that in my presentation I am attempting to present Perl strings from a character set agnostic perspective. So, even though there is a strong bias for Perl to treat character ordinals > 255 as Unicode code-points, I don't want people to automatically think Unicode when encountering one of these "non-legacy characters".
I'm just wondering if there is an established term. Perhaps "extended/large character ordinal"? It would help as in the sentence: "If your string contains a ___, Perl will assume your string represents Unicode code-points." ER