ietf-xml-mime
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Re: [ietf-types] Registration of media typeimage/svg+xml

2010-11-18 23:37:12

Hello Chris, others,

On 2010/11/19 7:52, Chris Lilley wrote:
This is an updated registration request, incorporating some feedback
from Ned Freed<ned(_dot_)freed(_at_)mrochek(_dot_)com>  and Julian 
Reschke<julian(_dot_)reschke(_at_)gmx(_dot_)de>

I agree with Ned and Julian. This registration now looks good to me, except for a little detail pointed out below.

As for why I was very uneasy with mentioning .svgz in the Mime Media Type registration of image/svg+xml, please see the following excerpt from a conversation between Larry Masinter and Henri Sivonen (http://lists.w3.org/Archives/Public/www-tag/2010Nov/0053.html):

>>>>
> What were the problems with image/svg+xml, image/jp2 and/or video/mp4?

The problem with image/svg+xml is that after a decade of deployment and W3C REC status, the type still isn't in the registry. Even if the IETF experts found something wrong with the type, it would be way too late to stop its deployment, so there's really no point in subjecting it to expert review at this point.
>>>>

>>>>
> As for image/svg+xml not being used for 'XML' format. I think this is a 3023bis issue?

Do you mean sending gzipped data as image/svg+xml without Content-Encoding: gzip?
>>>>

I concluded (I hope erroneously) that there was gzipped SVG content out there that was sent with a naked Content-Type: image/svg+xml, and that some people in the industry thought that that was just okay. It is very clear that it is not okay, and that the registry should not at all suggest that it would be okay.


Type name:

     image

Subtype name:

     svg+xml

Required parameters:

     None.

Optional parameters:

     charset

     Same as application/xml media type, as specified in [RFC3023] or
     it's successors.

Encoding considerations:

     Same as for application/xml. See [RFC3023], section 3.2 or it's
     successors.

Security considerations:

     As with other XML types and as noted in [RFC3023] section 10,
     repeated expansion of maliciously constructed XML entities can be
     used to consume large amounts of memory, which may cause XML
     processors in constrained environments to fail.

     Several SVG elements may cause arbitrary URIs to be referenced. In
     this case, the security issues of [RFC3986], section 7, should be
     considered.

     In common with HTML, SVG documents may reference external media
     such as images, audio, video, style sheets, and scripting
     languages. Scripting languages are executable content. In this
     case, the security considerations in the Media Type registrations
     for those formats shall apply.

     In addition, because of the extensibility features for SVG and of
     XML in general, it is possible that "image/svg+xml" may describe
     content that has security implications beyond those described
     here. However, if the processor follows only the normative
     semantics of this specification, this content will be outside the

"this specification" doesn't work when the registration template is taken out of the SVG spec. Either say "the SVG specification" or explicitly reference a specific version of the specification.


     SVG namespace and shall be ignored. Only in the case where the
     processor recognizes and processes the additional content, or
     where further processing of that content is dispatched to other
     processors, would security issues potentially arise. And in that
     case, they would fall outside the domain of this registration
     document.

Interoperability considerations:

     This specification describes processing semantics that dictate

Same problem here.

     behavior that must be followed when dealing with, among other
     things, unrecognized elements and attributes, both in the SVG
     namespace and in other namespaces.

     Because SVG is extensible, conformant "image/svg+xml" processors
     must expect that content received is well-formed XML, but it
     cannot be guaranteed that the content is valid to a particular DTD
     or Schema or that the processor will recognize all of the elements
     and attributes in the document.

     SVG has a published Test Suite and associated implementation
     report showing which implementations passed which tests at the
     time of the report. This information is periodically updated as
     new tests are added or as implementations improve.

Published specification:

     This media type registration is extracted from Appendix P of the
     SVG 1.1 specification. http://www.w3.org/TR/SVG/

Applications that use this media type:

     SVG is used by Web browsers, often in conjunction with HTML; by
     mobile phones and digital cameras, as a format for interchange of
     graphical assets in desk top publishing, for industrial process
     visualization, display signage, and many other applications which
     require scalable static or interactive graphical capability.

Additional information:

     Magic number(s):
     File extension(s):
         svg, svgz (if gzip-compressed)
     Macintosh file type code(s):
         "svg " (all lowercase, with a space character as the fourth
         letter), "svgz" (all lowercase, if gzip-compressed).
     Macintosh Universal Type Identifier code:
         org.w3c.svg conforms to public.image and to public.xml
     Windows Clipboard Name:
         "SVG Image"
     Fragment Identifiers
         For documents labeled as application/svg+xml, the fragment
         identifier notation is that for application/xml, as specified
         in RFC 3023 or its successors, plus the SVG-specific SVG Views
         syntax described in the SVG specification.

Person&  email address to contact for further information:

     Chris Lilley, Doug Schepers (member-svg-media-type(_at_)w3(_dot_)org).

Intended usage:

     COMMON

Restrictions on usage:

     None

Author:

     The SVG specification is a work product of the World Wide Web Consortium's 
SVG Working Group.

Change controller:

     The W3C has change control over this specification.

And same problem here again. Actually, in this case, I'm under the impression that "Change controller" refers to the change controller of the registration, not the specification (which would be the same, but would be written differently). But I might be wrong.

Regards,    Martin.

--
#-# Martin J. Dürst, Professor, Aoyama Gakuin University
#-# http://www.sw.it.aoyama.ac.jp   
mailto:duerst(_at_)it(_dot_)aoyama(_dot_)ac(_dot_)jp