text html xhtml An atom:feed must have an atom:author unless all of its atom:entry children have an atom:author. An atom:entry must have at least one atom:link element with a rel attribute of 'alternate' or an atom:content. An atom:entry must have an atom:author if its feed does not. text html xhtml 1 [^:]* .+/.+ [A-Za-z]{1,8}(-[A-Za-z0-9]{1,8})* .+@.+ xml:base xml:lang