Re: Relative URLs, // and ;

Chris Newman (Chris.Newman@innosoft.com)
Mon, 27 Jan 1997 13:34:24 -0800 (PST)


Date: Mon, 27 Jan 1997 13:34:24 -0800 (PST)
From: Chris Newman <Chris.Newman@innosoft.com>
Subject: Re: Relative URLs, // and ;
In-Reply-To: <3.0.32.19970127133440.007dcc20@hq.lcs.mit.edu>
To: Tim Berners-Lee <timbl@w3.org>
Cc: IETF URI list <uri@bunyip.com>
Message-Id: <Pine.SOL.3.95.970127132934.28359Q-100000@eleanor.innosoft.com>

On Mon, 27 Jan 1997, Tim Berners-Lee wrote:
> > > How is ';' involved in relative URLs?
> 
> Semicolons were introduced to allow elements to be specified by name rather
> than
> position, for spaces which were best seen as matrices rather than trees.
> In this case it is only sensible for relative URls which start with ";" to
> take a
> set of attribute values which are different.  This implies
> 	1. attributes can only occur once (unless you have a syntax for removing a
> 	   particular occurrence) and
> 	2. a missed value is equivalent to an unspecified value
> 	(so you can remove an occurrence by setting its value to empty)
> 	3. attributes are unordered
> 
> So relative to
> 	//moremaps.com/us/ma/cambridge;scale=50000;roads=main
> or the equivalent
> 	//moremaps.com/us/ma/cambridge;roads=main;scale=50000
> 
> URI	;scale=25000
> gives	//moremaps.com/us/ma/cambridge;scale=25000;roads=main
> 
> and	;roads
> gives	//moremaps.com/us/ma/cambridge;scale=50000
> 
> and	;roads=
> gives	//moremaps.com/us/ma/cambridge;scale=50000;roads=
> 
> and	;rivers=all
> gives	//moremaps.com/us/ma/cambridge;scale=50000;roads=main;rivers=all

I very much like this model.  Unfortunately, RFC 1808 seems to contradict
this model.  It seems to say that if the relative URL includes any
parameter, it replaces *all* the parameters of the base URL.  This is
certainly a problem for the IMAP URL scheme.