Re: Registration of media typeimage/svg+xml

Chris Lilley <> Thu, 18 November 2010 22:24 UTC

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Date: Thu, 18 Nov 2010 23:22:49 +0100
From: Chris Lilley <>
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To: Ned Freed <>
CC: Julian Reschke <>,, <>, Alexey Melnikov <>
Subject: Re: Registration of media typeimage/svg+xml
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On Thursday, November 18, 2010, 10:26:51 PM, Ned wrote:

>> On 18.11.2010 21:01, Chris Lilley wrote:
 read BCP 13, RFC 4288 section 4.6 "Security requirements" where you will find
>> >
>> >        A media type that employs compression may provide an opportunity
>> >        for sending a small amount of data that, when received and
>> >        evaluated, expands enormously to consume all of the recipient's
>> >        resources.  All media types SHOULD state whether or not they
>> >        employ compression, and if they do they should discuss
>> >        what  steps need to be taken to avoid such attacks.

NF> Read the section again. It is clearly talking about media types that employ
NF> compression *internally*, not compression done at other layers.

NF> Any media type can, and often is, compressed at other layers. Discussion
NF> of such actions has no business being in any particular media type
NF> registration.


NF> If, however, the answer is never - and I'm pretty sure it is - then all mention
NF> of compression needs to be dropped from this registration, as it is doing
NF> nothing useful and is just making things unclear. At most you might want a note
NF> about it in the encoding consideration sections saying external compression is
NF> often used with this type. Again, lots of media types are compressed at other
NF> layers; this has nothing to do with the image/svg+xml media type specifically.

In that case I can remove the section.

Julian, does that satisfy your concern as well?

 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups