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Re: xml:base (was Re: IRI meets RDF meets HTTP redirect)

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Thu, 19 Apr 2007 12:26:36 +0100
Message-ID: <462751EC.3030901@hpl.hp.com>
To: Chris Lilley <chris@w3.org>
CC: Sandro Hawke <sandro@w3.org>, John Cowan <cowan@ccil.org>, semantic-web@w3.org, www-international@w3.org


Oh good. So a base-uri function, which doesn't do any fetching, also 
doesn't do any %-escaping?

Jeremy

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.
> 
> 

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Received on Thursday, 19 April 2007 11:26:54 GMT

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