User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; de; rv:1.9) Gecko/2008052906 Firefox/3.0 Build Identifier: IGNORE and RCDATA (and other marked sections, accept CDATA) result in a parsing error in a XML documents. Reproducible: Always
Btw: IGNORE is already supported for HTML documents.
http://wiki.whatwg.org/wiki/HTML_vs._XHTML#Parsing In HTML, the title and textarea elements are parsed as RCDATA. (Note: The definition of RCDATA differs from that in SGML and there is no RCDATA in XML). -> invalid