protected function _normalizeFormFields($fields)
    {
        $_options = [
            'on' => 'both'
        ];

        $_defaults = [
            '_create' => $_options
        ];

        $result = [];

        $result['_create'] = $_defaults['_create'];

        foreach ($fields as $name => $options) {
            if (is_array($options)) {
                $result[$name] = array_merge($_options, $options);
            } else {
                $result[$options] = $_options;
            }
        }
        return $result;
    }