diff --git a/debian/var/models/example.xml b/debian/var/models/example.xml
index ffe815a..4a23fd4 100644
--- a/debian/var/models/example.xml
+++ b/debian/var/models/example.xml
@@ -13,20 +13,21 @@
 
        <version>1.0</version>
 
+       <ref id="texte" date="1629830000" author="Jean" lang="fr">Ref</ref>
     </identity>
 
     <!-- Model parameters -->
     <parameters id="texte" date="0" author="Gaston Lagaffe">
         <simulation>
-            <max_thread value="0"/>
-            <max_cycles value="13"/>
+            <max_thread>0</max_thread>
+            <max_cycles>13</max_cycles>
 
         </simulation>
 
         <space-param>
-            <dimension value="1"/>
-            <size value="39"/>
-            <site_multiplicity value="2"/>
+            <dimension>1</dimension>
+            <size>39</size>
+            <site_multiplicity>2</site_multiplicity>
 
         </space-param>
 
@@ -105,21 +106,21 @@
         </if>
 
         <then>
-          <quote>
+          <quote lang="fr">
             Therefore I can (and I want to) move it to its next east location
 
           </quote>
 
           <arrow x="0" y="0" z="0" site="1" weight="0"/>
           <arrow x="1" y="0" z="0" site="0" weight="0">
-            <quote>The identified dimer no more exists  ( :-(( </quote>
+            <quote lang="fr">The identified dimer no more exists  ( :-(( </quote>
 
           </arrow>
 
           <arrow x="1" y="0" z="0" site="1" weight="1"/>
 
           <arrow x="2" y="0" z="0" site="0" weight="1">
-            <quote>
+            <quote lang="fr">
               Happily, it is now rebuilt at its east location  ( ;-))
 
             </quote>
@@ -132,9 +133,4 @@
 
     </transitions>
 
-    <!-- Non context-specific tags, designed to annotate anything -->
-    <ref id="texte" date="1629830000" author="Jean" lang="ref"></ref>
-
-    <quote id="texte" date="1629830000" author="Jean" lang="ref"></quote>
-
 </gem-graph-model>
diff --git a/debian/var/models/example.xmls b/debian/var/models/example.xmls
index 85ed563..fbc0094 100644
--- a/debian/var/models/example.xmls
+++ b/debian/var/models/example.xmls
@@ -1,34 +1,40 @@
-<?xml version="1.0"?>
+<?xml version="1.0" encoding="UTF-8"?>
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
-
-<!-- https://www.freeformatter.com/xml-validator-xsd.html -->
-<!-- https://www.w3schools.com/xml/el_attribute.asp  -->
-<!-- use="required" is NOT allowed in attributes declarations-->
-<!-- To know : Attribute 'name' Cannot Appear In Element 'element'.-->
-
-<!-- xs:element name="name" type="xs:string"/ -->
-<!-- Cos-element-consistent: Error For Type '#AnonType_identitygem-graph-model'.
-     Multiple Elements With Name 'name', With Different Types, Appear In The Model Group. -->
-
 <xs:attribute name="id" type="xs:string"/>
-<xs:attribute name="date" type="xs:integer"/>  <!--TODO  type ? -->
+<xs:attribute name="date" type="xs:integer"/>
 <xs:attribute name="name" type="xs:string"/>
 <xs:attribute name="lang" type="xs:string"/>
-<xs:attribute name="value" type="xs:integer"/> <!--TODO  WARNING: It's an integer !-->
-<xs:attribute name="owner" type="xs:integer"/>
+<xs:attribute name="owner" type="xs:string"/>
+<xs:attribute name="owner_id" type="xs:integer"/>
 <xs:attribute name="author" type="xs:string"/>
 <xs:attribute name="version" type="xs:float"/>
+<xs:attribute name="sequence" type="xs:integer"/>
 <xs:attribute name="probability" type="xs:integer"/>
+<xs:attribute name="parent" type="xs:string"/>
 
-<!-- TO EVALUATE   Consider using 'group' (?) or NOT -->
-<!-- https://www.w3schools.com/xml/schema_complex_indicators.asp -->
-<!-- TO EVALUATE   Other definitions of an arrow (coord origin + dest,...) -->
-<!-- TO EVALUATE   Hypercubes pave the space => add a potential dimension 'w':
-     <xs:attribute name="w" type="xs:integer" default="0"/>-->
 
-<xs:element name="arrow">  <!-- TODO   Consider using 'group' : -->
-<!-- https://www.w3schools.com/xml/schema_complex_indicators.asp -->
+<xs:element name="a_string" type="xs:string"/>
+
+<xs:element name="ref">
     <xs:complexType>
+        <xs:simpleContent>
+            <xs:extension base="xs:string">
+              <xs:attribute ref="id"/>
+              <xs:attribute ref="date"/>
+              <xs:attribute ref="author"/>
+              <xs:attribute ref="lang" use="required"/>
+            </xs:extension>
+        </xs:simpleContent>
+    </xs:complexType>
+</xs:element>
+
+<xs:element name="quote" substitutionGroup="ref"/>
+
+<xs:element name="arrow">
+    <xs:complexType>
+        <xs:sequence>
+            <xs:element minOccurs="0" ref="quote"/>
+        </xs:sequence>
         <xs:attribute name="x" type="xs:integer" default="1"/>
         <xs:attribute name="y" type="xs:integer" default="0"/>
         <xs:attribute name="z" type="xs:integer" default="0"/>
@@ -37,16 +43,6 @@
     </xs:complexType>
 </xs:element>
 
-<!-- A state can be connex or not.   A connex state is an object.
-     A transition goes from an origin (state) to a target.
-
-    Therefore, element 'State' is used in
-     - objects definitions,
-     - initial and produced/computed states declarations,
-     - origin and target declarations of a transition.
-
-     What attributes should always be associated to a state ? -->
-
 <xs:element name="state">
     <xs:complexType>
     <xs:sequence minOccurs="1" maxOccurs="unbounded">
@@ -58,14 +54,49 @@
     </xs:complexType>
 </xs:element>
 
-<xs:element name="transition">
+<xs:element name="object" substitutionGroup="state"/>
+
+<xs:element name="space">
     <xs:complexType>
-    <xs:sequence minOccurs="2" maxOccurs="2"> <!-- TODO ... Cannot use 'length' -->
-        <xs:element ref="state"/>
+    <xs:sequence minOccurs="1" maxOccurs="unbounded">
+        <xs:element ref="arrow"/>
     </xs:sequence>
     <xs:attribute ref="id" use="required"/>
     <xs:attribute ref="date" use="required"/>
     <xs:attribute ref="author" use="required"/>
+    <xs:attribute ref="sequence" use="required"/>
+    </xs:complexType>
+</xs:element>
+
+<xs:element name="if">
+    <xs:complexType>
+    <xs:sequence minOccurs="0" maxOccurs="unbounded">
+        <xs:element minOccurs="0" ref="quote"/>
+        <xs:element ref="arrow"/>
+    </xs:sequence>
+    </xs:complexType>
+</xs:element>
+
+<xs:element name="then">
+    <xs:complexType>
+    <xs:sequence minOccurs="0" maxOccurs="unbounded">
+        <xs:element minOccurs="0" ref="quote"/>
+        <xs:element ref="arrow"/>
+    </xs:sequence>
+    </xs:complexType>
+</xs:element>
+
+<xs:element name="transition">
+    <xs:complexType>
+        <xs:sequence minOccurs="1" maxOccurs="1">
+            <xs:element minOccurs="0" ref="quote"/>
+            <xs:element ref="if"/>
+            <xs:element ref="then"/>
+        </xs:sequence>
+    <xs:attribute ref="id" use="required"/>
+    <xs:attribute ref="date" use="required"/>
+    <xs:attribute ref="author" use="required"/>
+    <xs:attribute ref="parent" use="required"/>
     <xs:attribute ref="probability" use="required"/>
     </xs:complexType>
 </xs:element>
@@ -73,70 +104,44 @@
 <xs:element name="gem-graph-model">
 <xs:complexType>
 <xs:sequence>
-
     <xs:element name="identity">
         <xs:complexType>
-        <xs:sequence>
-
-            <xs:element name="name" type="xs:string"/>
-            <xs:element name="owner" type="xs:integer"/>
-            <xs:element name="date" type="xs:integer"/>
-            <xs:element name="version" type="xs:float"/>
-
-        </xs:sequence>
+          <xs:sequence>
+              <xs:element name="name" type="xs:string"/>
+              <xs:element name="owner" type="xs:string"/>
+              <xs:element name="owner_id" type="xs:integer"/>
+              <xs:element name="date" type="xs:integer"/>
+              <xs:element name="version" type="xs:float"/>
+              <xs:element minOccurs="0" ref="ref"/>
+          </xs:sequence>
         </xs:complexType>
     </xs:element>
 
-    <xs:element name="parameters">
+        <xs:element name="parameters">
         <xs:complexType>
         <xs:sequence>
 
-            <xs:element name="modelization">
+            <xs:element name="simulation">
                 <xs:complexType>
                 <xs:sequence>
 
-                    <xs:element name="max_thread">
-                        <xs:complexType>
-                            <xs:attribute ref="value" use="required"/>
-                        </xs:complexType>
-                    </xs:element>
+                    <xs:element name="max_thread"/>
 
-                    <xs:element name="max_cycles">
-                        <xs:complexType>
-                            <xs:attribute ref="value" use="required"/>
-                        </xs:complexType>
-                    </xs:element>
+                    <xs:element name="max_cycles"/>
 
                 </xs:sequence>
                 </xs:complexType>
             </xs:element>
 
-            <xs:element name="space">
+            <xs:element name="space-param">
                 <xs:complexType>
                 <xs:sequence>
 
-                    <xs:element name="dimension">
-                        <xs:complexType>
-                            <xs:attribute ref="value" use="required"/>
-                        </xs:complexType>
-                    </xs:element>
+                    <xs:element name="dimension"/>
 
-                    <xs:element name="size">
-                        <xs:complexType>
-                            <xs:attribute ref="value" use="required"/>
-                        </xs:complexType>
-                    </xs:element>
+                    <xs:element name="size"/>
 
-                    <xs:element name="site_multiplicity">
-                        <xs:complexType>
-                            <xs:attribute ref="value" use="required"/>
-                        </xs:complexType>
-                    </xs:element>
-
-                    <xs:element name="boundaries">
-                        <xs:complexType>
-                        </xs:complexType>
-                    </xs:element>
+                    <xs:element name="site_multiplicity"/>
 
               </xs:sequence>
               </xs:complexType>
@@ -152,7 +157,7 @@
       <xs:element name="objects">
           <xs:complexType>
           <xs:sequence minOccurs="1" maxOccurs="unbounded">
-              <xs:element ref="state"/>  <!--An object is a connex state -->
+              <xs:element ref="state"/>
           </xs:sequence>
           <xs:attribute ref="id" use="required"/>
           <xs:attribute ref="date" use="required"/>
@@ -160,14 +165,10 @@
           </xs:complexType>
       </xs:element>
 
-      <!--An initial state is made of at least one object -->
-      <xs:element ref="state"/>
-
-      <!--An produced state is made of at least one object -->
-      <xs:element name="produced_states">
+      <xs:element name="savestates">
           <xs:complexType>
           <xs:sequence minOccurs="0" maxOccurs="unbounded">
-              <xs:element ref="state"/>
+              <xs:element ref="space"/>
           </xs:sequence>
           <xs:attribute ref="id" use="required"/>
           <xs:attribute ref="date" use="required"/>
@@ -186,12 +187,8 @@
           </xs:complexType>
       </xs:element>
 
-
-      <xs:element name="ref" type="xs:string"/>
-
-      <xs:element name="quote" type="xs:string"/>
-
 </xs:sequence>
+<xs:attribute ref="version" use="required"/>
 </xs:complexType>
 </xs:element>
 </xs:schema>