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Re: SVG12: charset parameter for image/svg+xml

From: Chris Lilley <chris@w3.org>
Date: Mon, 1 Nov 2004 21:39:09 +0100
Message-ID: <1834429884.20041101213909@w3.org>
To: Bjoern Hoehrmann <derhoermi@gmx.net>
Cc: www-svg@w3.org, ietf-types@iana.org

On Monday, November 1, 2004, 9:14:02 PM, Bjoern wrote:

BH> * Chris Lilley wrote:
>>BH>  which is expensive and unlikely to happen. In fact, a number
>>BH> of deployed tools already don't do that, for example the W3C Markup
>>BH> Validator would need to be updated with special code for image/svg+xml
>>BH> in order to comply with the registration.
>>
>>Incorrect; see above.

BH> The W3C Markup Validator considers resources such as

BH>   Content-Type: image/svg+xml;charset=iso-8859-1

BH>   <?xml version='1.0' encoding='utf-8'?>
BH>   ...

BH> ISO-8859-1 encoded.


Yes, there are two inconsistent pieces of metadata and the markup
validator correctly applies the rules to determine which to use. Note
that the example above, if saved to disk and re-opened, is not well
formed. This is undesirable. Lots of content is processed from local
disk, on servers and on clients.

The markup validator does the correct thing also in this case

Content-Type: image/svg+xml

  <?xml version='1.0' encoding='utf-8'?>
  ...

  and this one

Content-Type: image/svg+xml

  <?xml version='1.0'?>
  ...


  and this one

Content-Type: image/svg+xml

  <?xml version='1.0' encoding="koi-8-r"?>
  ...  

  as per RFC 3023.
  
BH> If it is incorrect that the W3C Markup Validator needs to change you
BH> either want that all processors treat the resource ISO-8859-1
BH> encoded in which case there is not really a point in not allowing an
BH> optional charset parameter,

I agree, there is no point in an optional charset parameter. Thats why
the registration for svg doesn't have one.

BH> or you want two classes of non- interoperable processors, where some
BH> consider it ISO-8859-1 and others consider it UTF-8. Which one is
BH> it?

That is the current situation, yes. Some processors do one and some do
the other. As you note, its undesirable. As you note, I don't want this.

The TAG would like to see mutually inconsistent duplicate metadata
reduced or eliminated.




-- 
 Chris Lilley                    mailto:chris@w3.org
 Chair, W3C SVG Working Group
 Member, W3C Technical Architecture Group
Received on Monday, 1 November 2004 20:39:10 UTC

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