After a brief stint of being the elected Joomla! RAD Layer and trying to be developed in tandem with Joomla! (even
    though the FOF develoeprs were never given ahead warning of the merge window closing, making this nigh impossible),
    FOF is now being developed separately from Joomla!. In order to avoid naming clashes we have changed the prefix of
    all FOF classes from FOF to F0F (F-zero-F). Moreover, the installation path changed from
    JPATH_LIBRARIES . '/fof' to JPATH_LIBRARIES . '/f0f' (again: that's f-zero-f). The same
    goes for the FOF_INCLUDED constant which is now called F0F_INCLUDED (again: that's
    f-zero-f). If you want to use this new version please remember to change these instances from FOF to
    F0F.
Tips and important notes regarding backwards compatibility:
require_once JPATH_LIBRARIES . '/fof/include.php'; require_once JPATH_LIBRARIES . '/f0f/include.php';
        at the top of their template overrides to load both versions: FOF 2.2.x (f-oh-f prefix) included in Joomla! 3.2
        or later and FOF 2.3.x (f-zero-f prefix). Thanks to our strong backwards compatibility this is bound to work.
    FOFModel::getInstance to get a model object from a class
        which now extends F0FModel (FOF 2.3.x) it will work, as long as the double require_once is present in their
        code.