Correctly Categorizing Chatterboxen

Those of you who’ve seen my slide deck, perhaps with an eye to performing it yourself, per my suggestion-invitation, may recall that slide wherein I go:

4D: Coxeter (polytopes, extended Euclideanism, perpendiculars)
4D: Einstein (3D space + imaginary time)
4D: RBF (a container as a concept primitively “4-eyed”)