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Re: PROPOSAL: Restrict @prefix declaration to the root element

From: Ivan Herman <ivan@w3.org>
Date: Tue, 2 Aug 2011 13:51:41 +0200
Cc: RDFa WG <public-rdfa-wg@w3.org>
Message-Id: <84FFC55D-0E5F-472E-BF5F-7FB239E354F5@w3.org>
To: Manu Sporny <msporny@digitalbazaar.com>
This proposal would lead to major issues with character encoding, see


Executive summary of that mail: HTML5 works with content sniffing to find out the character encoding of the source (looking for a relevant <meta> element in the head). This is done by HTML parsers, too, not only browsers. Having lots of prefix declarations in the <html> elements might lead to erroneous character encoding in the literal objects of the generated RDF; and there is no real defense against that (unless the HTTP return header provides a correct character encoding, but that is not always the case).

Actually, the advise (currently in the Primer, too) is _not_ to put too many @prefix declaration in the <html> element to avoid such issues, but put them into, say, the <body> element.

I do not think we should do this.


On Jul 19, 2011, at 04:54 , Manu Sporny wrote:

> This proposal was raised during the telecon last week[1]. Since document
> authors can declare @prefix anywhere in the document, they could
> introduce authoring mistakes due to copy-paste. That is, if they do not
> pay attention to where the @prefix is declared, they may accidentally
> attempt to express triples that do not have a CURIE prefix defined.
> While a number of people in the group feel that copy-paste issues are
> not really that prevalent, limiting the use of @prefix to just the root
> element of the document may decrease the possibility of copy-paste
> errors. That is, copying from one place to another place in the document
> would not be affected by @prefix declaration.
> The down-side to this is that all Web page authors do not have access to
> the root element in a document, which is typically set by the content
> management system. This would disallow people that know what they're
> doing from expressing triples in their sub-sections of the document -
> such as blog articles or comment posts.
> PROPOSAL: Limit @prefix declaration to the root element in the document.
> -- manu
> [1]http://www.w3.org/2010/02/rdfa/meetings/2011-07-14#ISSUE__2d_96__3a__Document_not_ready
> -- 
> Manu Sporny (skype: msporny, twitter: manusporny)
> President/CEO - Digital Bazaar, Inc.
> blog: PaySwarm Developer Tools and Demo Released
> http://digitalbazaar.com/2011/05/05/payswarm-sandbox/

Ivan Herman, W3C Semantic Web Activity Lead
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Received on Tuesday, 2 August 2011 11:50:03 UTC

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