How universal are roguelike character mappings? Is there some central bit of knowledge that all the developers refer to to decide whether 'b' should be a bear or a beholder?
Letters are almost always monsters, but which monsters are in which game is anyone's guess.
The Art of Unix Programming: http://www.catb.org/~esr/writings/taoup/html/
GNU Coding Standards: http://www.gnu.org/prep/standards/standards.html
Standard list of long options: http://www.gnu.org/prep/standards/standards.html#Option-Tabl...
Short options from -a to -z: http://www.catb.org/~esr/writings/taoup/html/ch10s05.html
...so this is the "serious" version of what you're describing.