xemacs21-supportel 21.4.22-14ubuntu1 (amd64 binary) in ubuntu xenial

 XEmacs is a full fledged programming language with a mail reader,
 news reader, info browser, web browser, calendar, specialized editor
 for more programming languages and other formats than most people
 encounter in a lifetime, and much more.
 .
 This package contains all the non-necessary library files for
 XEmacs. The xemacs21-support package contains the compiled versions
 of these files.
 .
 The major reason to install this package is if you want to learn
 elisp or modify the libraries for your specific installation.