diff --git a/authzgroupsoo.php b/authzgroupsoo.php
index c40c122..ffd0167 100644
--- a/authzgroupsoo.php
+++ b/authzgroupsoo.php
@@ -85,6 +85,7 @@ class authzgroupsoo
       {
       case "2": $res[$k] = "RW"; break;
       case "1": $res[$k] = "RO"; break;
+      case "0": $res[$k] = "NO"; break;
       default:
         throw new \Exception (dgettext ("domframework",
                                        "Unknown right stored"), 500);
@@ -318,7 +319,7 @@ class authzgroupsoo
       "idright"  => array ("integer", "not null", "autoincrement"),
       "idgroup"  => array ("integer", "not null"),
       "idobject" => array ("integer", "not null"),
-      "right"    => array ("varchar(2)", "not null"), // RO,RW
+      "right"    => array ("varchar(2)", "not null"), // NO, RO,RW
       "comment"  => array ("varchar(255)")));
     $this->dbRight->primary ("idright");
     $this->dbRight->unique (array ("idright", array ("idgroup","idobject")));
@@ -1037,9 +1038,12 @@ class authzgroupsoo
     {
     case "RW": $right=2;break;
     case "RO": $right=1;break;
+    // Normally, the NO is not used as the entry should be removed and the user
+    // will have the same result. The NO allow to force the value.
+    case "NO": $right=0;break;
     default:
       throw new \Exception (dgettext ("domframework",
-                                      "Unknown right provided (RO/RW only)"),
+                                      "Unknown right provided (NO/RO/RW only)"),
                            500);
     }
     $groups = $this->groupRead ($module, $group);
@@ -1079,9 +1083,10 @@ class authzgroupsoo
     {
     case "2": $right=2;break;
     case "1": $right=1;break;
+    case "0": $right=0;break;
     default:
       throw new \Exception (dgettext ("domframework",
-                                      "Unknown right provided (RO/RW only)"),
+                                      "Unknown right provided (0/1/2 only)"),
                                       500);
     }
     $groups = $this->groupReadByID ($module, $idgroup);
@@ -1161,9 +1166,10 @@ class authzgroupsoo
     {
     case "RW": $newright=2;break;
     case "RO": $newright=1;break;
+    case "NO": $newright=0;break;
     default:
       throw new \Exception (dgettext ("domframework",
-                                      "Unknown right provided (RO/RW only)"),
+                                      "Unknown right provided (NO/RO/RW only)"),
                                       500);
     }
     $idrights = $this->rightRead ($module, $group, $object);
@@ -1196,9 +1202,10 @@ class authzgroupsoo
     {
     case "2": $newright=2;break;
     case "1": $newright=1;break;
+    case "0": $newright=0;break;
     default:
       throw new \Exception (dgettext ("domframework",
-                                      "Unknown right provided (RO/RW only)"),
+                                      "Unknown right provided (0/1/2 only)"),
                                       500);
     }
     $idrights = $this->rightReadByID ($module, $idright);
@@ -1336,7 +1343,7 @@ class authzgroupsoo
     */
   public function rightTypes ()
   {
-    return array ("1" => "RO", "2" => "RW");
+    return array ("0" => "NO", "1" => "RO", "2" => "RW");
   }
 
   /** Check if the provided data are compilant with the group specification