Nice discuss on c.t.t.:
https://groups.google.com/group/comp.text.tex/browse_thread/thread/ccbccddc56566af1?hl=de#
https://groups.google.com/group/comp.text.tex/browse_thread/thread/0eb972f5fc36a115?hl=de#
https://groups.google.com/group/comp.text.tex/browse_thread/thread/29822a8234aa3feb?hl=de#