HP 50g Graphing Calculator - Manual (Page 809)

Page B-11
Notice that the ~„ combination is used mainly to enter the lower-case
letters of the English alphabet (A through Z). The numbers, mathematical
symbols (-, +,
× ), decimal point (.), and the space (SPC) are the same as the
main functions of these keys. The ENTER and CONT keys also work as their
main function even when the ~„ combination is used.
Alpha ~„ functions of the calculator’s keyboard