When I run httpd on my test platform, there is a log saying "Cannot combine ForceLanguagePriority options None and Prefer" and "Cannot combine ForceLanguagePriority options None and Fallback", but there is no message about "None" in the document of "ForceLanguagePriority"(http://httpd.apache.org/docs/2.4/mod/mod_negotiation.html#forcelanguagepriority). So is it a misleading log message or an incomplete document?