diff --git a/examples/conceptual/Concept_ExampleInvariant.thy b/examples/conceptual/Concept_ExampleInvariant.thy
index 67b6297a..aca91fc5 100644
--- a/examples/conceptual/Concept_ExampleInvariant.thy
+++ b/examples/conceptual/Concept_ExampleInvariant.thy
@@ -20,14 +20,15 @@ The implementor of an ontology must know what he does ...
 
 text\<open>Setting a sample invariant, which simply produces some side-effect:\<close>
 setup\<open>DOF_core.update_class_invariant "Conceptual.A" (fn oid => 
-                                                       fn ctxt => 
-                                                        (writeln ("sample echo : "^oid); true))\<close>
+                                                       fn {is_monitor = b} =>
+                                                        fn ctxt => 
+                                                           (writeln ("sample echo : "^oid); true))\<close>
 
 subsection*[b::A, x = "5"] \<open> Lorem ipsum dolor sit amet, ... \<close>
 
 
 text\<open>Setting a sample invariant, referring to attribute value "x":\<close>
-ML\<open>fun check_A_invariant oid ctxt = 
+ML\<open>fun check_A_invariant oid {is_monitor:bool} ctxt = 
       let val term =  AttributeAccess.calc_attr_access ctxt "x" oid @{here}
           val (@{typ "int"},x_value) = HOLogic.dest_number term
       in  if x_value > 5 then error("class A invariant violation") else true end
@@ -62,7 +63,7 @@ that instances of class C occur more often as those of class D; note that this i
 to take sub-classing into account:
 \<close>
 
-ML\<open>fun check_M_invariant oid ctxt = 
+ML\<open>fun check_M_invariant oid {is_monitor}  ctxt = 
       let val term =  AttributeAccess.calc_attr_access ctxt "trace" oid @{here}
           fun conv (Const(@{const_name "Pair"},_) $ Const(s,_) $ S) = (s, HOLogic.dest_string S)
           val string_pair_list = map conv (HOLogic.dest_list term)