diff --git a/htdocs/conf/conf.php.example b/htdocs/conf/conf.php.example
index c3c174232d8eb0609456b081f16af50b1cfdc04f..fd42c8fd319a92a3f0c46f73ed641dde5f19e664 100644
--- a/htdocs/conf/conf.php.example
+++ b/htdocs/conf/conf.php.example
@@ -14,7 +14,9 @@
 
 # dolibarr_main_url_root
 # This parameter defines the root URL of your Dolibarr index.php page.
-# It must link to the directory htdocs.
+# It must link to the directory htdocs. It is autodetected with version
+# 3.1 and more but required to show full url bookmarks for some 
+# services (ie: agenda rss export url, ...)
 # Examples:
 # $dolibarr_main_url_root='http://localhost';
 # $dolibarr_main_url_root='http://mydolibarrvirtualhost';