function php($data) {
// Set value to true unless set otherwise below
$valid = true;

      if (!parent::php($data)) return false; // required fields failed.

// do we have a OriginalTranslatio value? If not, why continue validating? ;)
if (isset($data['OriginalTranslation'])) {
      $origTokens = $this->getTokens($data['OriginalTranslation']);
      $newTokens = $this->getTokens($data['Translation']);

      // determine if they are the same
      $valid = count($origTokens) == count($newTokens);

      if ($valid && count($origTokens) > 0) {
         // Counts are the same, so iterate over both arrays and ensure they are compatible.
         for ($i = 0; $i < count($origTokens); $i++) {
            // @todo This requires an exact match. For example, %10d and %d won't match, but should.
            if ($origTokens[$i] != $newTokens[$i]) $valid = false;
         }
      }
}

      if (!$valid) {
         $this->validationError(
            'Translation',
            _t('Form.FIELDSIGNATUREMISMATCH', "The value substitution tokens in the new translation must match the tokens in the original translation string"),
            "invalid"
         );
      }

      return $valid;
   }