Dunno about tr, but here's one way of doing this: 
my $str = "YOSEMITE SAM";
$str =~ s/(\w+)/\u\L$1/g;

[download]

Note that \w+ might not match your definition of word, but you should be able to modify it to suit.

-- Dan

In reply to Re: Changing case on a word boundary by zigdon
in thread Changing case on a word boundary by blue_cowdawg

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