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Re: TWO Change proposals for ISSUE-41 : Distributed Extensibility

From: Maciej Stachowiak <mjs@apple.com>
Date: Tue, 16 Mar 2010 18:23:29 -0700
Cc: HTMLwg <public-html@w3.org>
Message-id: <9C9A7A71-8919-4276-93E6-F4A8004E1E32@apple.com>
To: "Ennals, Robert" <robert.ennals@intel.com>
Hi Rob,

Thanks for your submissions. I have recorded both of your Change  
Proposals on the issue status page:

I have left the call for volunteers open, in case anyone else chooses  
to submit any additional proposals.


On Mar 15, 2010, at 8:28 PM, Ennals, Robert wrote:

> As promised, I have created a change proposal for ISSUE-41,  
> Distributed Extensibility.
> In fact, I’ve created two. One proposal is basically my original  
> proposal that I promised to write up as a proposal. This is designed  
> with the aim of preserving compatibility with XML namespaces while  
> taming their worst effects. The other proposal is one I now think I  
> prefer, and is designed with the aim of minimizing the possible  
> risks from extensions to HTML, and making things as simple as  
> possible to users, at the cost of making it more awkward to use  
> existing XML specifications in HTML documents.
> They are here:
> Proposal X: compatible with XML namespaces:
> http://www.w3.org/html/wg/wiki/ChangeProposals/fixedprefixlikexml
> Proposal Y: tries to give a better fallback and backwards-compat  
> story:
> http://www.w3.org/html/wg/wiki/ChangeProposals/fixedprefixsimple
> The main differences between the two are:
> ·         X uses “:” as the prefix separator, while Y uses “-“
> ·         X puts a prefixed node into the namespace defined by  
> XMLNS, or null if there is no XMLNS, while Y has no namespace. X’s  
> behavior is incompatible with current HTML5 behavior, but compatible  
> with XMLs. The alternative is to follow current HTML5 behavior, but  
> that means that XML and HTML parses of the same document have  
> different DOM trees, which is arguably even worse.
> ·         X allows an HTML document to mix in existing XML specs. Y  
> requires existing XML specs to be reformulated as an attribute-based  
> “-“ prefixed extension in order to be mixed into HTML documents –  
> but the resulting document has a better fall-back story.
> ·         X allows an extension spec to define new element types  
> while Y doesn’t (authors should write <tag prefix-foo> instead,  
> where “tag” is whatever tag is most appropriate in the current  
> version of HTML)
> The ideas in common are:
> ·         A prefix has a fixed meaning.
> ·         A prefix should be registered in a wiki (or something else  
> similar) to avoid clashes.
> ·         An experimental prefix starting with “x-“ can be used  
> without registering.
> ·         A document will parse the same in XML and HTML.
> ·         A document that uses extensions is not valid HTML, but is  
> valid “extended HTML”.
> I initially liked X, but after thinking about it for a while,  
> decided that the compatibility issues with “:” and the potential  
> fallback problems from extensions defining their own element types  
> outweighed the advantage of being able to mix in existing XML specs  
> unmodified – resulting in Y.
> Thoughts?
> -Rob

Received on Wednesday, 17 March 2010 01:24:02 UTC

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