code for both Xemacs and GNU emacs

Hello What is the best way to provide code which can be understood by both emacsen. I have seen so far: Code for both emacsen (if (featurep 'xemacs) code for xemacs ) But what if I had code specifically for GNU emacs. Would the following be a good idea? Taken from the .emacs skeleton file. (defvar running-xemacs (string-match "XEmacs\\|Lucid" emacs-version)) Code for both emacsen (cond (running-xemacs Code for xemacs )) (cond ((and (not running-xemacs) (> emacs-major-version 19)) Code for gnus goes here )) Or are there better solutions? Thanks Uwe Brauer