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Re: Is the P-word? (Was: TAG Decision on Rescinding the request to the HTML WG to develop a polyglot guide)

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Wed, 23 Jan 2013 10:11:49 +0100
To: David Sheets <kosmo.zb@gmail.com>
Cc: Henri Sivonen <hsivonen@iki.fi>, Daniel Glazman <daniel@glazman.org>, Sam Ruby <rubys@intertwingly.net>, Noah Mendelsohn <nrm@arcanedomain.com>, "www-tag@w3.org List" <www-tag@w3.org>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <20130123101149251672.0cd0fbe3@xn--mlform-iua.no>
David Sheets, Tue, 22 Jan 2013 21:18:00 -0800:

> What is the reason that
> <http://dev.w3.org/html5/html-xhtml-author-guide/#content-type> says
> <blockquote>
> The HTTP Content-Type: header has no extra rules or restrictions,
> whereas polyglot markup does not use the http-equiv="Content-Type"
> declaration on the meta element.
> </blockquote>

The Polyglot Markup spec limits itself to define a subset of the HTML5 
spec, which permits meta@charset=UTF-8 in both XHTML code and HTML 
code, whereas the HTML5 spec only permits meta@http-equiv in HTML code.

> This suggests to me that putting something like
> <meta http-equiv="Content-Type" content="application/xhtml+xml" />

A case could be made for allowing 'text/html;charset=UTF-8' in XHTML5 
since meta@charset has somewhat limited support outside the GUI browser 
world. For instance, Microsoft Word and Open Office doesn't support 
<meta charset="UTF-8"/>. Which, I have to admit, feels like a pain in 
polyglot’s robustness principle ass. ;-) But then again: If you 
export/download a Google Docs document (from Google Drive) as HTML, you 
will find that it contains no encoding declaration (and no DOCTYPE for 
that matter) - all the non-ASCII is converted to numerical character 

> is a potential way to indicate to text/html consumers that this
> representation is also parseable by an XML parser and interpretable by
> an XHTML renderer.
> Is this ill-advised for some reason? Is there a pitfall here of which
> I am ignorant?
> It would be nice to embed useful metadata indicating that the present
> representation is intended to have identical semantics under different
> media types' interpretations. This would give multi-modal consumers a
> means to leverage both HTML and XML processing on the document if so
> instructed.

If you meant that one could include two meta based encoding decalraiton 
elements in the same document, then HTML5 forbids that as well.

leif halvard silli
Received on Wednesday, 23 January 2013 09:12:21 UTC

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