use strict;
use warnings;

while (<>) {
    s{(<[^?<>]*\.[^<>]*>)}{
        (my $tagname = $1 ) =~ tr/.//d;
        $tagname;
    }eg;
    print;
}

##</code><code>##

<?xml version="1.0"?>
<TOP>
  <SUB>
    <THIS>STUFF</THIS>
    <SOME.TYPE>T</SOME.TYPE>
    <SOME.OTHER.TYPE>BLAH</SOME.OTHER.TYPE>
  </SUB>
</TOP>

##</code><code>##

<?xml version="1.0"?>
<TOP>
  <SUB>
    <THIS>STUFF</THIS>
    <SOMETYPE>T</SOMETYPE>
    <SOMEOTHERTYPE>BLAH</SOMEOTHERTYPE>
  </SUB>
</TOP>