22048 2013-05-15 13:15:13 +0000 relative path state and drive letter using vertical bar 2013-07-03 12:04:16 +0000 1 1 1 Unclassified WHATWG URL unspecified PC Windows NT RESOLVED INVALID P2 normal Unsorted 1 naruse annevk mike sideshowbarker+urlspec oldest_to_newest 87723 0 naruse 2013-05-15 13:15:13 +0000 http://url.spec.whatwg.org/#relative-path-state Though URL file:///c| looks valid in this spec (see also http://msdn.microsoft.com/en-us/library/aa767731(v=vs.85).aspx ), it raises parse error. url parser's relative path state's "If c is not a URL code point and not "%", parse error." denies "|" because URL code points doesn't include "|". It should allow "|". A fix can be change relative path state's clause 4 as following and remove duplicating 1.4.1. * If url's scheme is "file", url's path is the empty list, buffer consists of one code point, of which the first is an ASCII alpha, and c is "|", append ":" to buffer. * Otherwise, if c is not a URL code point and not "%", parse error. * Otherwise, if c is "%" and remaining does not start with two ASCII hex digits, parse error. * Otherwise, utf-8 percent encode c using the default encode set, and append the result to buffer. 90218 1 annevk 2013-07-03 09:54:52 +0000 Given that you can write it using : instead (and it will be normalized to that) I think giving an error for that situation is fine. 90221 2 naruse 2013-07-03 12:04:16 +0000 Ah, yes. That "parse error" only notifies it is error, and it doesn't abort process. It looks I did misunnderstand.