I opened this version of the spec:
Version: 2.0 Rev A
Status: Final Release
Release: 9 July 2010
It talks about FacesContext.isPartialRequest() - Note this method does not
exist. A similar is available on PartialViewContext.
Also it talks about FacesContext.isAjaxRequest() AND
PartialViewContext.isAjaxRequest() - Note: the first one does not exist as well