protected function _createSubFormAtIndex($index) {
        $class = 'garp-subform';
        if ($this->isDuplicatable()) {
            $class .= ' duplicatable';
        }
        $subform = new Garp_Form_SubForm(array(
            'name' => (string)$index,
            'class' => $class
        ));
        if (is_array($this->_duplicatableOptions)) {
            if (!empty($this->_duplicatableOptions['buttonClass'])) {
                $subform->getDecorator('HtmlTag')->setOption('data-button-class', $this->_duplicatableOptions['buttonClass']);
            }
            if (!empty($this->_duplicatableOptions['buttonAddClass'])) {
                $subform->getDecorator('HtmlTag')->setOption('data-button-add-class', $this->_duplicatableOptions['buttonAddClass']);
            }
            if (!empty($this->_duplicatableOptions['buttonRemoveClass'])) {
                $subform->getDecorator('HtmlTag')->setOption('data-button-remove-class', $this->_duplicatableOptions['buttonRemoveClass']);
            }
            if (!empty($this->_duplicatableOptions['buttonAddLabel'])) {
                $subform->getDecorator('HtmlTag')->setOption('data-button-add-text', $this->_duplicatableOptions['buttonAddLabel']);
            }
            if (!empty($this->_duplicatableOptions['buttonRemoveLabel'])) {
                $subform->getDecorator('HtmlTag')->setOption('data-button-remove-text', $this->_duplicatableOptions['buttonRemoveLabel']);
            }
            if (!empty($this->_duplicatableOptions['skipElements'])) {
                $subform->getDecorator('HtmlTag')->setOption('data-skip-elements', $this->_duplicatableOptions['skipElements']);
            }
            if (!empty($this->_duplicatableOptions['afterDuplicate'])) {
                $subform->getDecorator('HtmlTag')->setOption('data-after-duplicate', $this->_duplicatableOptions['afterDuplicate']);
            }
        }
        return $subform;
    }