diff --git a/Isabelle_DOF-Unit-Tests/Concept_OntoReferencing.thy b/Isabelle_DOF-Unit-Tests/Concept_OntoReferencing.thy
index c2b1f9e1..5a915fbc 100644
--- a/Isabelle_DOF-Unit-Tests/Concept_OntoReferencing.thy
+++ b/Isabelle_DOF-Unit-Tests/Concept_OntoReferencing.thy
@@ -84,11 +84,12 @@ text*[d::D, a1 = "X3"] \<open> ... phasellus amet id massa nunc, pede suscipit r
 text\<open>Not only text-elements are "ontology-aware", proofs and code can this be too !\<close>
                                                                           references\<close>
 \<comment> \<open>Referencing from and to a ML-code context:\<close>
+(*<*)
 ML*[c4::C, z = "Some @{A \<open>a1\<close>}"]\<open>
 fun fac x = if x  = 0  then 1 else x * (fac(x-1))
 val v = \<^value_>\<open>A.x (the (z @{C \<open>c4\<close>}))\<close> |> HOLogic.dest_number |> snd |> fac
 \<close>
-
+(*>*)
 definition*[a2::A, x=5, level="Some 1"] xx' where "xx' \<equiv> A.x @{A \<open>a1\<close>}" if "A.x @{A \<open>a1\<close>} = 5"
 
 lemma*[e5::E] testtest : "xx + A.x @{A \<open>a1\<close>} = yy + A.x @{A \<open>a1\<close>} \<Longrightarrow> xx = yy" by simp
@@ -140,7 +141,7 @@ update_instance*[f::F,b:="{(@{docitem  \<open>a\<close>}::A,@{docitem  \<open>c1
 section\<open>Closing the Monitor and testing the Results.\<close>
 
 close_monitor*[struct]
-text\<open>@{A a0}\<close>
+
 text\<open>And the trace of the monitor is:\<close>
 ML\<open>val trace = @{trace_attribute struct}\<close>
 ML\<open>@{assert} (trace = 
diff --git a/Isabelle_DOF-Unit-Tests/High_Level_Syntax_Invariants.thy b/Isabelle_DOF-Unit-Tests/High_Level_Syntax_Invariants.thy
index eb5f373e..8500e310 100644
--- a/Isabelle_DOF-Unit-Tests/High_Level_Syntax_Invariants.thy
+++ b/Isabelle_DOF-Unit-Tests/High_Level_Syntax_Invariants.thy
@@ -1,11 +1,52 @@
+(*************************************************************************
+ * Copyright (C) 
+ *               2019-2023 The University of Exeter 
+ *               2018-2023 The University of Paris-Saclay
+ *               2018      The University of Sheffield
+ *
+ * License:
+ *   This program can be redistributed and/or modified under the terms
+ *   of the 2-clause BSD-style license.
+ *
+ *   SPDX-License-Identifier: BSD-2-Clause
+ *************************************************************************)
+
 chapter\<open>High level syntax Invariants\<close>
 
 theory High_Level_Syntax_Invariants
   imports "Isabelle_DOF.Isa_DOF"
-  "Isabelle_DOF-Unit-Tests_document"
-
+          "Isabelle_DOF-Unit-Tests_document"
+          TestKit
 begin
 
+section\<open>Test Purpose.\<close>
+text\<open>
+  Without invariants, ontological classes as such are too liberal in many situations.
+  Similarly to UML constraints, invariants or hand-programmed checking functions
+  can be added in ODL ontologies in order to constrain class instances or
+  (via monitor traces) impose structural constraints over an entire document.
+
+  While hand-programmed checking functions were tested in test-case 
+  \<^verbatim>\<open>Concept_Example_Low_Level_Invariant\<close>, in this text case, we test 
+  high-level invariants, i.e. data-constraints speicified as executable 
+  HOL-predicates in the @{theory_text \<open>invariant\<close>} clause of ODL definitions.
+
+  To enable the checking of the invariants, the \<open>invariants_checking\<close>
+  theory attribute must be set:\<close>
+
+
+section\<open>The Scenario.\<close>
+
+text\<open> This is merely an example that shows that the generated invariants
+      fit nicely together; i.e. allow for sensible consistency and invariant
+      preservation proofs related to ontological matchings. \<close>
+
+
+text\<open>Using HOL, we can define a mapping between two ontologies.
+  It is called ontology matching or ontology alignment.
+  Here is an example which show how to map two classes.
+  HOL also allows us to map the invariants (ontological rules) of the classes!\<close>
+
 text\<open>
   Ontological classes as described so far are too liberal in many situations.
   There is a first high-level syntax implementation for class invariants.