code: function(value, identifier) {
        var
          $form = $(this),
          matchingValue
        ;
        if( $('[data-validate="'+ identifier +'"]').length > 0 ) {
          matchingValue = $('[data-validate="'+ identifier +'"]').val();
        }
        else if($('#' + identifier).length > 0) {
          matchingValue = $('#' + identifier).val();
        }
        else if($('[name="' + identifier +'"]').length > 0) {
          matchingValue = $('[name="' + identifier + '"]').val();
        }
        else if( $('[name="' + identifier +'[]"]').length > 0 ) {
          matchingValue = $('[name="' + identifier +'[]"]');
        }
        return (matchingValue !== undefined)
          ? ( value.toString() == matchingValue.toString() )
          : false
        ;
      }
docs: matches another field