Ah, but nobody's reply has solved the problem of swapping the case of letters while obeying locale (so that accented letters are handled). 

s/([[:upper:]]*)([[:lower:]]*)/\L$1\U$2/g;

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- tye        

In reply to Re: uppercase/lowercase in a single expression (locale) by tye
in thread uppercase/lowercase in a single expression by greatshots

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