diff --git a/mef/model_organization.rst b/mef/model_organization.rst
index 916b4cb..44f01ad 100644
--- a/mef/model_organization.rst
+++ b/mef/model_organization.rst
@@ -60,44 +60,23 @@ For even medium size PSA models this assumption not compatible with Quality Cont
 Moreover, such a monolithic organization of data would be very hard to manage
 when several persons work together on the same model.
 
-A first way to split the model into several files is to use the XML notion of entities:
-in any XML file, it is possible to declare file entities in the preamble,
-and to include them in the body of the document.
-This mechanism is exemplified below.
-
-.. code-block:: xml
-
-    <?xml version="1.0" ?>
-
-    <!DOCTYPE SMRF [
-    <!ENTITY file1 SYSTEM "file1.xml">
-    <!ENTITY file2 SYSTEM "file2.xml">
-    ]>
-    <smrf>
-        ...
-        &file1;
-        ...
-        &file2;
-        ...
-    </smrf>
-
-This mechanism, however, has the drawback
-that XML tools have to actually include the files into the document,
-hence, making its manipulation heavier.
-
-The Model Exchange Format proposes another simple mechanism to achieve the same goal:
-the tag include.
+The Model Exchange Format utilizes XInclude_,
+general purpose XML Include (W3C Candidate Recommendation),
+which allows splitting the model in flexible and unconstrained ways.
 This tag can be inserted at any place in a document.
-Its effect is to load the content of the given file into the model.
+Its effect is to include the content of the given file into the model.
 
 .. code-block:: xml
 
-    <opsa-mef>
+    <opsa-mef xmlns:xi="http://www.w3.org/2001/XInclude">
         ...
-        <include file="basic-events.xml"/>
+        <xi:include href="basic-events.xml"/>
         ...
     </opsa-mef>
 
+.. _XInclude: https://www.w3.org/TR/xinclude/
+
+
 Organization of a Model
 =======================
 
diff --git a/mef/schema/fault_tree.rnc b/mef/schema/fault_tree.rnc
index 3db2121..a22ad13 100644
--- a/mef/schema/fault_tree.rnc
+++ b/mef/schema/fault_tree.rnc
@@ -7,8 +7,7 @@ fault-tree-definition =
      | CCF-group-definition
      | event-definition
      | component-definition
-     | parameter-definition
-     | include-directive)*
+     | parameter-definition)*
   }
 
 component-definition =
@@ -21,8 +20,7 @@ component-definition =
      | CCF-group-definition
      | event-definition
      | component-definition
-     | parameter-definition
-     | include-directive)*
+     | parameter-definition)*
   }
 
 role = attribute role { "private" | "public" }
@@ -31,8 +29,7 @@ model-data =
   element model-data {
     (house-event-definition
      | basic-event-definition
-     | parameter-definition
-     | include-directive)*
+     | parameter-definition)*
   }
 
 event-definition =
diff --git a/mef/schema/mef.rnc b/mef/schema/mef.rnc
index 74f4e9f..fd8affb 100644
--- a/mef/schema/mef.rnc
+++ b/mef/schema/mef.rnc
@@ -7,11 +7,6 @@ reference =
     xsd:NCName { pattern = "([^\-.]+(-[^\-.]+)*)(\.\i[^\-.]*(-[^\-.]+)*)*" }
   }
 
-include-directive =
-  element include {
-    attribute file { xsd:string }
-  }
-
 include "model.rnc"
 include "label_and_attributes.rnc"
 
diff --git a/mef/schema/model.rnc b/mef/schema/model.rnc
index 20c3a05..091a5da 100644
--- a/mef/schema/model.rnc
+++ b/mef/schema/model.rnc
@@ -13,6 +13,5 @@ model =
      | initiating-event-definition
      | fault-tree-definition
      | substitution-definition
-     | CCF-group-definition
-     | include-directive)*
+     | CCF-group-definition)*
   }