Contextual keys?

[Joe Horn]

Just FYI, the 35s manual says (page 1-26), "The a b/c symbol under the [.] key is a reminder that the [.] key is used twice for fraction entry." This was copied verbatim from the 33s manual (page 1-22), since the 33s also has "a b/c" below the [.] key in the same color as A-Z (black). That in turn was copied verbatim from the 32SII manual (page 1-18), whose "a b/c" is also the same color as A-Z (either white or very light blue... I can't tell). 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.