public function format_boolean($field)
    {
        $value = $this->current_row[$field.'_original'];
        $label = $this->current_row[$field];

        if ($value === true || $value === 1 || $value === 'Y') {
            $this->current_row_html[$field] =
                '<div align=center>'.
                    '<i class="icon-check">'.($label!==$value ? $label : $this->app->_('yes')).'</i>'.
                '</div>';
        } else {
            $this->current_row_html[$field] = '';
            /*
            $this->current_row_html[$field] =
                '<div align=center>'.
                    '<i class="icon-check-empty">'.($label!==$value ? $label : $this->app->_('no')).'</i>'.
                '</div>';
            */
        }
    }