HP 48gII - Manual (Page 761)

Page 23-4
say they line feed character , you will see at the left side of the bottom of
the screen the keystroke sequence to get such character ( . for this case) and
the numerical code corresponding to the character (10 in this case).
Characters that are not defined appear as a dark square in the characters list
( ) and show (
None ) at the bottom of the display, even though a numerical
code exists for all of them. Numerical characters show the corresponding
number at the bottom of the display.
Letters show the code
α (i.e., ~) followed by the corresponding letter, for
example, when you highlight M, you will see αM displayed at the lower left
side of the screen, indicating the use of ~m. On the other hand, m shows
the keystroke combination α M, or ~„m.
Greek characters, such as
σ, will show the code α S , or ~‚s. Some
characters, like ρ, do not have a keystroke sequence associated with them.
Therefore, the only way to obtain such characters is through the character list
by highlighting the desired character and pressing
@ECHO1@ or @ECHO@.
Use
@ECHO1@ to copy one character to the stack and return immediately to
normal calculator display. Use @ECHO@ to copy a series of characters to the
stack. To return to normal calculator display use $.
See Appendix D for more details on the use of special characters. Also,
Appendix G shows shortcuts for producing special characters.