Contextual keys?

[Orome]

Joe Horn Wrote:  So the concept of [a b/c] and A-Z being "modal primary keys" or "contextual keys" goes back to 1991, when the 32SII first appeared.

Indeed! It's much clearer there that they are intended to have the same semantics (I should have looked at the 32SII first).

Interestingly, on the 32SII [ON] is identified (correctly) as "contextual" as well. So arguably the semantics were in place (or anticipated) farther back.