+-------------------------------------------------------------------------------
+
+.. _pf_tag_platform:
+
+<platform>
+----------
+
+**Parent tags:** none (this is the root tag of every file) |br|
+**Children tags:** :ref:`pf_tag_config` (must come first),
+:ref:`pf_tag_cluster`, :ref:`pf_tag_cabinet`, :ref:`pf_tag_peer`,
+:ref:`pf_tag_zone`, :ref:`pf_tag_trace`, :ref:`pf_tag_trace_connect` |br|
+**Attributes:**
+
+:``version``: Version of the DTD, describing the whole XML format.
+ This versionning allow future evolutions, even if we
+ avoid backward-incompatible changes. The current version
+ is **4.1**. The ``simgrid_update_xml`` program can
+ upgrade most of the past platform files to the most recent
+ formalism.
+
+-------------------------------------------------------------------------------