Re: Request for review: 3023bis (XML media types) makes significant changes

From: Martin J. Dürst <>
Date: Wed, 18 Dec 2013 16:59:10 +0900

Hello Henry,

Some comments on your specific questions, which may trigger some
additional discussion.

On 2013/12/12 1:43, Henry S. Thompson wrote:
> I'm one of the editors of a proposed replacement for RFC3023 [1], the
> media type registration for application/xml, text/xml and 3 others.
> The draft replacement [2] includes several significant changes in the
> handling of information about character encoding:
> * In cases where conflicting information is supplied (from charset
> param, BOM and/or XML encoding declaration) it give a BOM, if
> present, authoritative status;

I'm a bit uneasy about the fact that we now have BOM (internal) -
charset (external) - encoding (internal), i.e.
internal-external-internal, but I guess there is lots of experience in
HTML 5 for giving the BOM precedence. Also, it will be extremely rare to
have something that looks like a BOM but isn't, and this combined with
the fact that XML balks on encoding errors should make things quite robust.

> * It recommends against the use of UTF-32.

UTF-32 has some (limited) appeal for internal representation, but none
really on the network, and media types are for network interchange, so
this should be fine, too.

Regards, Martin.

> The interoperability situation in this space is currently poor, with
> some tools treating a charset parameter as authoritative, but the HTML
> 5 spec and most browsers preferring the BOM. The goal of the draft is
> to specify an approach which will promote convergence, while
> minimising the risk of damage from backward incompatibilities.
> Since these changes overlap with a wide range of technologies, I'm
> seeking review outside the relevant IETF mailing list
> ( -- please take a look if you can, particularly
> at Section 3 [3] and Appendix C [4].
> Thanks,
> ht
> [1]
> [2]
> [3]
> [4]
Received on Wed Dec 18 2013 - 02:02:47 CST

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