--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc/book/en/04-00-define-schema.en.txt	Thu Nov 20 20:14:23 2008 +0100
@@ -0,0 +1,22 @@
+.. -*- coding: utf-8 -*-
+
+Data model definition (*schema*)
+================================
+
+The schema is the core piece of a `CubicWeb` application as it defines
+the data model handled. It is based on entities types already defined
+in the `CubicWeb` standard library and others, more specific, we would 
+expect to find in one or more Python files under the `schema` directory.
+
+At this point, it is important to make clear the difference between
+relation type and relation definition: a relation type is only a relation
+name with potentially other additionnal properties (see XXXX), whereas a 
+relation definition is a complete triplet 
+"<subject entity type> <relation type> <object entity type>". 
+A relation type could have been implied if none is related to a 
+relation definition of the schema.
+
+
+.. include:: 04-01-schema-stdlib.en.txt
+.. include:: 04-02-schema-definition.en.txt
+