Re: Extended URL for frames

Sun, 15 Sep 1996 18:04:07 -0500 (EST)

Date: Sun, 15 Sep 1996 18:04:07 -0500 (EST)
From: Foteos Macrides <MACRIDES@SCI.WFBR.EDU>
Subject: Re: Extended URL for frames
Message-id: <01I9IM1G4HH4005LBE@SCI.WFBR.EDU> (Jon Degenhardt) wrote:
>Daniel W. Connolly <> writes:
>> Hmmm... I'm pretty sure I've seen implementations that scan
>> from the right for the first #, and consider that to be the
>> split between the URL and the fragment identifier.
>This is the first step in the parsing algorithm described in RFC 1808,
>"Relative Uniform Resource Locators" (

	RFC1738 was written back in the days when the assumption was that
there'd be only one '#', as a fragment delimiter, and that in all other
cases it would be hex escaped.  It also recommends hex escaping for URL
schemes which do no normally have a fragment.  So based on that, the
direction of parsing for the '#' is irrelevant.  The libwww, through the
current W3C Reference Library, parses for the fragment from right to
left, and thus will use the last one if there is more than one unescaped
'#'.  One would expect right to left parsing for NS, since it started off
as a rewrite of XMosaic, for the Mosaics themselves, for Arena, probably
Amaya, and for most if not all old and moderately old browsers (i.e.,
they'll "fail" the  "test" as did NS).

	The wording of RFC1808 instead indicates left to right parsing,
and implies that non-hex escaped '#'s can occur to the right of the one
which delimits the fragment.  The MSIE parser probably was guided by
RFC1808, which is probably why the "test" "worked" with it.


 Foteos Macrides            Worcester Foundation for Biomedical Research
 MACRIDES@SCI.WFBR.EDU         222 Maple Avenue, Shrewsbury, MA 01545