diff --git a/docs/USAGE b/docs/USAGE
index 4732872..1b533ce 100644
--- a/docs/USAGE
+++ b/docs/USAGE
@@ -198,6 +198,24 @@ The fields are defined by :
 The CSRF parameter is verify automatically when using $f->values ();
 In case of error, an exception is raised.
 
+10. Authentication / Authorization
+----------------------------------
+The Authentication/Authorization module permits to allow/deny access to objects.
+The user must be validated before using a information. It is based on Unix
+model, with users/groups/modbits, files (objects) with owner/group/modbits.
+To do that, you can use a table in your database:
+    $auth = new authorizationdb ();
+    $auth->connectdb ($this->database["dsn"], $this->database["username"],
+                      $this->database["password"],
+                      $this->database["driver_options"]);
+Then add the objects with the rights :
+    $auth->add ("/module/<object>", $auth->authiduser,
+                                   reset ($auth->authgroups), 0755);
+You can remove the objects with :
+    $auth->del ("/module/<object>");
+You can see if the user can access to the object with READ, WRITE, EXECUTE :
+    $auth->validate ("/module/<object>")
+
 XX. CLI usage
 -------------
 The DomFramework is designed to be used in console line too.