So dom style http://xmltwig.org

#!/usr/bin/perl --
use strict; 
use warnings; 
use XML::Twig;
my $t = XML::Twig->new( pretty_print => 'indented' );
$t->xparse(q{<roooooo>
  <citreference id="mycite">
    <linktext>
      <keyword conref="ds"/> support for IPv6 addresses</linktext>
  </citreference>
  <moops></moops>
</roooooo>});
$t->print;
my( @links ) = $t->findnodes( '//linktext' );
my( $moops ) = $t->findnodes( '//moops' );
for my $link ( @links ){
    print $link->path, "\n";
    $link->cut->paste( $moops );
}
$t->print;
__END__
<roooooo>
  <citreference id="mycite">
    <linktext><keyword conref="ds"/> support for IPv6 addresses</linkt
+ext>
  </citreference>
  <moops></moops>
</roooooo>
/roooooo/citreference/linktext
<roooooo>
  <citreference id="mycite"></citreference>
  <moops>
    <linktext><keyword conref="ds"/> support for IPv6 addresses</linkt
+ext>
  </moops>
</roooooo>
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