Un update of the PLIB example

src/tests/Mapped_PILIB_Ontology.thy

@@ -3,6 +3,23 @@ theory Mapped_PILIB_Ontology
 
 begin
 
+text\<open>
+PLIB does not assume that all data sources use the same ontology. 
+Each data source may build its local ontology without any external reference. 
+It may also build it based upon one or several reference ontologies (i. e., standard ones). 
+A class of a local ontology may be described as subsumed by one or several other class(es) defined in other ontologies. 
+This means that each instance of the former is also instance of the latter. This relationship is named case-of. 
+Though case- of relationship the subsumed class may either import properties (their GUI and definitions are preserved) 
+or map properties (the properties are different but they are semantically equivalent) that are defined in the referenced class(es). 
+It may also define additional properties.
+\<close>
+
+text\<open>
+The following example is extract from this reference : 
+CONTEXT-EXPLICATION IN CONCEPTUAL ONTOLOGIES: PLIB ONTOLOGIES AND THEIR USE FOR INDUSTRIAL DATA
+Special issue of JAMS - Journal of Advanced Manufacturing Systems
+By GUY PIERRA
+\<close>
 text\<open>User Ontology\<close>
 
 onto_class Item =
@@ -74,4 +91,7 @@ definition U_Software_to_R_Software_morphism
           , version = U_Software.version \<sigma>
         \<rparr>" 
 
+
+
+
 end