diff --git a/doc/source/conf.py b/doc/source/conf.py
index ef0c86c77..41e53ac7f 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -39,6 +39,7 @@
     'sphinx.ext.autodoc',
     'sphinx.ext.mathjax',
     'sphinx.ext.viewcode',
+    'sphinx.ext.graphviz'
 ]
 
 # Math
diff --git a/doc/source/xmlrpc.rst b/doc/source/xmlrpc.rst
index fafbd636a..7063ba077 100644
--- a/doc/source/xmlrpc.rst
+++ b/doc/source/xmlrpc.rst
@@ -62,6 +62,17 @@ This is the list of method names:
    Return the aggregated state associated to the 
    infrastructure with ID ``infId``. 
    
+   The ``state`` can be
+
+   * ``pending``, At least one VM is still in initialization stage;
+   * ``running``, All the VMs are created successfully and running, but at least one of them are still in the configuration stage;
+   * ``configured``, All the VMs are running and contextualized;
+   * ``unconfigured``, All the VMs are running but at least one of them are not correctly contextualized;
+   * ``stopped``, All the VMs are stopped or suspended;
+   * ``off``, All the VMs are shutdown or removed from the infrastructure;
+   * ``failed``, There are at least one VM in status ``failed``.
+   * ``unknown``, There are at least one VM in status ``unknown``.
+
 ``GetInfrastructureRADL``
    :parameter 0: ``infId``: integer
    :parameter 1: ``auth``: array of structs