sub compare {
  # We ignore the standalone, opening and closing tags <ph />, <bpt x="y">, <ept x="z">, <i />

  my $cString1 = $_[0];
  my $cString2 = $_[1];

  $cString1 =~ s/\/?<(bpt|ept|ph|i)[^<>]*>//gsmi;
  $cString2 =~ s/\/?<(bpt|ept|ph|i)[^<>]*>//gsmi;

  ("$cString1" eq "$cString2") ? return 1 : return 0;
}

##</code><code>##

if (compare($unit{$x}{string1}, $string2)) {
  # Do some stuff
}