.. _reference.version:

``version``
==================

The format and version of the feed.

Here is the complete list of known feed types and versions that may be returned in ``version``:

============  ====================================================================================
``atom``      Atom (unknown or unrecognized version)
``atom01``    `Atom 0.1 <http://www.intertwingly.net/blog/1506.html>`_
``atom02``    `Atom 0.2 <http://diveintomark.org/public/2003/08/atom02spec.txt>`_
``atom03``    `Atom 0.3 <http://www.mnot.net/drafts/draft-nottingham-atom-format-02.html>`_
``atom10``    `Atom 1.0 <http://www.ietf.org/rfc/rfc4287>`_
``cdf``       `CDF <http://www.w3.org/TR/NOTE-CDFsubmit.html>`_
``rss``       :abbr:`RSS (Rich Site Summary)` (unknown or unrecognized version)
``rss090``    `RSS 0.90 <http://www.purplepages.ie/RSS/netscape/rss0.90.html>`_
``rss091n``   `Netscape RSS 0.91 <http://my.netscape.com/publish/formats/rss-spec-0.91.html>`_
``rss091u``   `Userland RSS 0.91 <http://backend.userland.com/rss091>`_
``rss092``    `RSS 0.92 <http://backend.userland.com/rss092>`_
``rss093``    `RSS 0.93 <http://backend.userland.com/rss093>`_
``rss094``    :abbr:`RSS (Rich Site Summary)` 0.94 (no accurate specification is known to exist)
``rss10``     `RSS 1.0 <http://purl.org/rss/1.0/>`_
``rss20``     `RSS 2.0 <http://blogs.law.harvard.edu/tech/rss>`_
============  ====================================================================================

If the feed type is completely unknown, ``version`` will be an empty string.

.. tip::

    This element always exists, although it may be an empty string if the version
    can not be determined.

.. seealso::

    `The Myth of RSS compatibility <http://web.archive.org/web/20110726002019/http://diveintomark.org/archives/2004/02/04/incompatible-rss>`_
        Mark Pilgrim's excellent analysis of the extraordinary variety of
        incompatibilities each version of "RSS" introduced.
