function add_mod_hatom_data($content) {
$iso8601_date = get_the_time('c');
$author = get_the_author();
$title = get_the_title();
if( is_single() ) {
$content .= '<div class="hatom-extra"><span class="entry-title">'.$title.'</span>
ultima modifica: <span class="updated"> '.$iso8601_date.'</span>
da <span class="author vcard"><span class="fn">'.$author.'</span></span></div>';
}
return $content;
}
add_filter('the_content', 'add_mod_hatom_data');