the blue ALPHA key, key (7,1), can be combined with some of the other keys
to activate the alternative functions shown in the keyboard.
For example, the P key, key(4,4), has the following six functions associated
Main function, to activate the SYMBolic menu
Left-shift function, to activate the MTH (Math) menu
Right-shift function, to activate the CATalog function
ALPHA function, to enter the upper-case letter P