diff --git a/docs/index.rst b/docs/index.rst
index dd15882..fdc2b08 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -40,6 +40,10 @@ An previous paper about this work is:
 The IS Model
 ************
 
+.. image:: ./is-model.png
+
+.. image:: ./is-model-er.png
+
 The Information System Model (henceforth IS Model) is a graph model with Entities as nodes and Relations as edges. 
 
 * Two typologies of entities are envisaged:
@@ -47,6 +51,7 @@ The Information System Model (henceforth IS Model) is a graph model with Entitie
 	* Resources, i.e. entities representing a description of "thing" to be managed:
 	
 		* Every Resource is described by a number of Facets.
+
 	* Facets, i.e. entities contributing to "build" a description of a Resource. Every facet, once attached to a Resource profile captures a certain aspect / characterization of the resource:
 	
 		* Every facet is characterised by a number of properties.
@@ -83,14 +88,54 @@ The Free Dictionary defines a facet as “One of numerous aspects, as of a subje
 
 
 ....
+Type Attributes
+===============
 
-********************************
-IS Model Base Concept Definition
-********************************
+Any Property defined in the schema is characterised by:
 
-Any extension of the IS Model will be defined as following
+Name: 
+	Property Name
 
- 
+Type:
+	The Type of the Property (e.g. String, Integer, ...). It can be a Basic Type or a Derived Type or a Complex Type
+
+Description:
+	The description of the Property. default=null.
+
+Mandatory (M):
+	Indicate if the Property is mandatory. default=false.
+
+ReadOnly (RO):
+	The Property cannot change its value. default=false.
+
+NotNull (NN):
+	Whether the property must assume a value diverse from 'null' or not. default=false
+
+Max (Max):
+	default=null
+
+Min (Min):
+	default=null
+
+Regex (Reg)):
+	A Regular Expression to validate the property value, default=null. A good online tool for regex is avalable at https://regex101.com/
+
+
+Basic Types
+-----------
+
+
+Derived Types
+-----------
+
+The following are obtained using a String as real type and adding a validation regex. 
+
+
+
+Complex Types
+-----------
+
+Any property defined by composing basic types, complex types and other complex types. Any complex type can be defined by extending Property type. 
 
 
 Property
diff --git a/docs/is-model-er.png b/docs/is-model-er.png
new file mode 100644
index 0000000..be9e408
Binary files /dev/null and b/docs/is-model-er.png differ
diff --git a/docs/is-model.png b/docs/is-model.png
new file mode 100644
index 0000000..3f2fa7e
Binary files /dev/null and b/docs/is-model.png differ