I also like that I got to include the Macintosh (well, ISO) symbols for "Shift" and "Backspace". The HP 42S has a backspace key but uses a generic "left arrow" for it. The HP 42s's shift key is just an orange block, to make it clearly associated with the orange text above every button. But without the luxury of colour-coding, I had to pick something more graphic to represent "shift", and what better choice than the glyph that the Mac used to represent the shift modifier in keyboard shortcuts?