Re: % in URIs

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Subject: % in URIs
Date: Tue, 02 Sep 2003 18:04:15 +0100

[...]

> I am not yet convinced that this materially affects RDF since we *never* 
> require the escaping to actually be performed, it is merely a theoretical 
> exercise that defines a set of strings. I believe that the set of strings 
> is the same whether or not % is itself escaped.
> 
> Jeremy

From reading RFC2396 I believe that this is not the case.  In particular,
my understanding is that http://foo.bar/oijoi% is not a legal absolute URI
with optional fragment identifier, nor is http://foo.bar/oijoi%xy

From RDF2396:

   Because the percent "%" character always has the reserved purpose of
   being the escape indicator, it must be escaped as "%25" in order to be
   used as data within a URI.  Implementers should be careful not to escape
   or unescape the same string more than once, since unescaping an already
   unescaped string might lead to misinterpreting a percent data character
   as another escaped character, or vice versa in the case of escaping an
   already escaped string.

There is lots more on escaping in RDF2396.  The RDF escaping mechanism
ignores most the subtleties involved.  

Peter F. Patel-Schneider

Received on Saturday, 6 September 2003 03:55:53 UTC