tr question (probably wrong list to ask, but ...)

This is probably the wrong list for this question, but is anyone  
willing to give me a clue why

$line =~ tr/+/ /;

would clip out the lead bytes of a shift-JIS string in a cgi script?

Come to think of it, I think it's being applied while the string is  
still hex-encoded, so it makes even less sense to me.

(I know, I should be letting the CGI module decode the url-encoded  
string. But I seem to be mis-understanding something fundamental  
here. Which is why a newbies list would probably be better for this  
question.)

Joel Rees
(waiting for a 3+GHz ARM processor to come out,
to test Steve's willingness to switch again.)