1st one is relatively minor: according our own manpage, upper and lower
classes must be sorted, but currently not.
2nd one is serious:
tr '[:lower:]' '[:upper:]'
(and vice versa) currently works only if upper and lower classes
have exact the same number of elements. When it is not true, like for
many ISO8859-x locales which have bigger amount of lowercase letters,
tr may do nasty things.
See this page
http://www.opengroup.org/onlinepubs/007908799/xcu/tr.html
for detailed description of desired tr behaviour in such cases.
