- From: Chris Lilley <chris@w3.org>
- Date: Thu, 19 Apr 2007 15:57:17 +0200
- To: Jeremy Carroll <jjc@hpl.hp.com>
- Cc: Sandro Hawke <sandro@w3.org>, John Cowan <cowan@ccil.org>, <semantic-web@w3.org>, <www-international@w3.org>
On Thursday, April 19, 2007, 1:26:36 PM, Jeremy wrote: JC> Oh good. So a base-uri function, which doesn't do any fetching, also JC> doesn't do any %-escaping? I would need to spec-spelunk to be sure but that would be my interpretation of the intent of the PER, yes. Specifically, two IRIs are the same if (following use of xml:base to do relative-to-absolute) they are the same Unicode strings. There is no need to hexify both of them, though IIRC RFC3987 does talk about doing that in theory. JC> Jeremy JC> Chris Lilley wrote: >> On Wednesday, April 18, 2007, 9:03:19 PM, Sandro wrote: >>>> The value of an xml:base attribute is not so limited: it can contain >>>> (almost) arbitrary Unicode, which is %-escaped before being used >>>> to alter the base URI property of the element on which it appears >>>> and the element's children. >> SH> Percent-escaping has got to be among the 10 most confusing and confused >> SH> subjects in the history of computing. :-) >> This is why its better if computers do it, and humans see the real characters. >> SH> My sense is that the 2001 XML Base Recommendation [1] is very confused >> SH> about how to handle percent-escaping. Of course, it long predated IRIs, >> SH> so this isn't so surprising. >> I agree that the newer PER is clearer. >> SH> There is a Proposed Edited Recommendation [2] which, to my mind, is much >> SH> clearer about this. It says, essentially, don't do percent-escaping. >> SH> XML is safe for Unicode, so just use Unicode. >> Which is pretty much what >> The set of characters allowed in xml:base attributes is the same as >> for XML, namely [Unicode]. However, some Unicode characters are >> disallowed from URI references, and thus processors must encode and >> escape these characters to obtain a valid URI reference from the >> attribute value. >> says. The improvement in the PER is to clarify that the 'processor' is >> the software which reads the XML attribute value and constructs a URI >> to fetch; not, as it could be read, the software which creates the XML >> document. -- Chris Lilley mailto:chris@w3.org Interaction Domain Leader Co-Chair, W3C SVG Working Group W3C Graphics Activity Lead Co-Chair, W3C Hypertext CG
Received on Thursday, 19 April 2007 13:57:42 UTC