About `name' in loadup.el

[Xue Fuqiao]

In lisp/loadup.el:

  (let ((name (concat "emacs-" emacs-version)))
    (while (string-match "[^-+_.a-zA-Z0-9]+" name)
      (setq name (concat (downcase (substring name 0 (match-beginning 0)))
                       "-"
                       (substring name (match-end 0)))))
    (message "Adding name %s" name)
    (add-name-to-file "emacs" name t))

I'm confused here.  What does this fragment of code do?  And when will
characters other than "-+_.a-zA-Z0-9" be in `emacs-version'?  Can
anybody help?  Thanks.

-- 
Best regards, Xue Fuqiao.
http://www.emacswiki.org/emacs/XueFuqiao