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[Fwd: [Moderator Action] Re: Some notes on SVG parsing in HTML 5]

From: Doug Schepers <schepers@w3.org>
Date: Wed, 25 Feb 2009 19:19:10 -0500
Message-ID: <49A5DFFE.6020402@w3.org>
To: SVG WG <public-svg-wg@w3.org>

-------- Original Message --------
From: Simon Pieters <simonp@opera.com>
Cc: public-svg-wg@w3.org

I thought I'd point out things that don't match my understanding of HTML5:

On Thu, 26 Feb 2009 00:14:12 +0100,  wrote:

> Hello WG.
> I’ve taken a brief look at the commented out SVG parsing language in
> HTML 5.  Below are some pertinent notes for ACTION-2395.  Something
> being a “parse error” means that the document is non-conforming.

It also means that a UA has the choise to continue parsing (using the 
rules given in the spec) or to abort parsing.

> Parsing this document:
>   <svg xmlns='http://www.w3.org/2000/svg'>
>     <circle r='100'/>
>   </svg>
> as text/html would be non-conforming, since it doesn't begin with an
> <html> tag,

No, <html> is optional, but lack of a doctype is a parse error. (Lack of 
<title> is not a parse error but a content model error.)

> Parsing this document:
>   <!DOCTYPE html>
>   <html>
>     <head>
>       <title></title>
>     </head>
>     <body>
>       <svg>
>         <circle r='100'/>
>       </svg>
>     </body>
>   </html>
> would be non-conforming, since the <svg> tag is missing an
> xmlns='http://www.w3.org/2000/svg' attribute.

No, xmlns is optional. If it is preset, it must have the right value, 

> SVG Tiny 1.2 elements aren't considered, and so <textArea> will parse
> as an HTML <textarea> element and break out of foreign content mode.

<textArea> *could* be supported, though.

> There's a comment <!--XXXSVG need to define processing for </script> to
> match HTML5's </script> processing --> but I'm not sure what processing
> this means.


Basically, it says how to run the script in a way that is compatible 
withhow browsers have to do it for HTML (in the face of, say, an 
external script that document.writes another external script that 
document.writes something).

> In foreign content mode, a <font> start tag with a color, face or size
> attribute will cause the document to be non-conforming.  <!-- the
> attributes here are required so that SVG <font> will go through as SVG
> but legacy <font>s won't -->

> The following start tags cause a parse error inside foreign content:
> b, big, blockquote, body, br, center, code, dd, div, dl, dt, em, embed,
> h1, h2, h3, h4, h5, h6, head, hr, i, img, li, listing, menu, meta, nobr,
> ol, p, pre, ruby, s, small, span, string, strike, sub, sup, tbale, tt,
> u, ul and var.  <!-- this list was determined empirically by studying
> over 6,000,000,000 pages that were specifically not XML pages -->

They are not parse errors in <foreignContent>, <title> or <desc>, 
though.Anywhere else (in SVG) would cause the tag to escape back to HTML 


   <svg> <title> <b>foo</b> </title> </svg>

is parsed as expected (svg and title are SVG elements, b is an HTML 
element), but

   <svg> <g> <b>foo</b> </g> </svg>

is a parse error and is parsed as if it were

   <svg> <g> </g></svg><b>foo</b>

Simon Pieters
Opera Software

-Doug Schepers
W3C Team Contact, SVG and WebApps WGs
Received on Thursday, 26 February 2009 00:19:26 UTC

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