efaq: X key translations for Emacs

 
 9.5 How do I set the X key “translations” for Emacs?
 ====================================================
 
 Emacs is not written using the Xt library by default, so there are no
 “translations” to be set.  (We aren’t sure how to set such translations
 if you do build Emacs with Xt; please let us know if you’ve done this!)
 
    The only way to affect the behavior of keys within Emacs is through
 ‘xmodmap’ (outside Emacs) or ‘define-key’ (inside Emacs).  The
 ‘define-key’ command should be used in conjunction with the
 ‘function-key-map’ map.  For instance,
 
      (define-key function-key-map [M-<TAB>] [?\M-\t])
 
 defines the ‘M-<TAB>’ key sequence.