layout of settings page not correct HTML

The documentation of placeholders is displayed as follows

    // Display the user documentation of placeholders supported by
    // this module
    foreach ($settings->placeholders as $name => $description) {
      $items .= '<dt>'.$name.'</dt>';
      $items .= '<dd>'.$description.'</dd>'."\n";
    }

This is not really easy to style if you want ot do the whole definition list as a block.
To make this part correct html you'd need to add a DL element to the code like this

    // Display the user documentation of placeholders supported by
    // this module
    if ($settings->placeholders) {
        $items .= "<dl>\n";
        foreach ($settings->placeholders as $name => $description) {
            $items .= '<dt>'.$name.'</dt>';
            $items .= '<dd>'.$description.'</dd>'."\n";
        }
        $items .= "</dl>\n";
    }