Some years ago I took some M28 gear to a steampunk show. I was concerned about how to get people to use a 3-row keyboard with LTRS/FIGS keys.
Then, Doh!, I just told people it is exactly like your iPhone. Kids had no difficulty with it at all.
Related to all this is the issue of keyboard layout.
It was not an issue in Baudot (Murray) code since that uses a 3 row
keyboard unique to it and uses the LTRS and FIGS codes to shift between
the two cases of characters above and below on each