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Re: ISSUE-27: rel-ownership - Chairs Solicit Proposals

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Wed, 30 Dec 2009 00:35:47 +0100
To: Mark Nottingham <mnot@mnot.net>, "Roy T. Fielding" <fielding@gbiv.com>
Cc: Toby Inkster <tai@g5n.co.uk>, Paul Cotton <Paul.Cotton@microsoft.com>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <20091230003547441690.4d33244b@xn--mlform-iua.no>
Hi Mark,

When you, Roy or anyone else makes bold claims about "confusion" about 
what HTML 4 says, then it would be extremely helpful if you could 
provide an exegesis that that demonstrate those claims.

I followed your pointer to Roy's message - and what did I see? I saw 
hat Roy has not read HTML 4 correctly. HTML 4 says _exactly_ what Roy 
says, namely: Links are not reversible. But relationships are. (That 
relationships are reversible doesn't mean that the _words_ for those 
relationships are reversible - @rev doesn't create antonyms ... of 
course.) 

I have provided an exegesis of what HTML 4 says which demonstrates that 
this is so [1][2]. I produced it without knowing about Roy's message - 
I came to this conclusion _solely_ by reading HTML 4.

It is indeed true, also, that HTML 4 could have used a clearer wording. 
But if one reads HTML 4 the same way that HTML 5 says one should read 
HTML 5 [3], then it ought to be pretty obvious that there is no other 
possible interpretation of HTML 4 than the one Roy have. In other 
words: HTML 4 is says the same that previous specifications has said.

If you or anyone have another interpretation of HTML 4, then please 
provide something that makes your interpretation credible. Or else we 
should put those claims aside as unfounded.

[1] http://lists.w3.org/Archives/Public/public-html/2009Dec/0409

[2] http://lists.w3.org/Archives/Public/public-html/2009Dec/0410

[3] 
http://dev.w3.org/html5/spec/Overview.html#how-to-read-this-specification


Leif Halvard Silli

Mark Nottingham, Wed, 30 Dec 2009 10:02:11 +1100:
> Hi Toby,
> 
> Regarding rev semantics - see Roy's message at:
>   http://www.w3.org/mid/2BDD98C6-F223-47DC-AF4B-BCBF6E232813@gbiv.com

> 
> This is part of a much larger discussion. While confusion is 
> certainly part of the problem -- and the rev="canonical" debacle was 
> an indication that it's pretty widespread -- there are also people 
> who have very clear but incompatible views of what rev means.
> 
> Thanks for the implementation ref; I have a very simple one in Python 
> at <http://gist.github.com/210535>. Any interest in working on a test 
> suite?
> 
> Cheers,
> 
> 
> 
> On 16/12/2009, at 11:23 PM, Toby Inkster wrote:
> 
>>> http://www.mnot.net/drafts/draft-nottingham-http-link-header-07.txt

>>> 
http://www.mnot.net/drafts/draft-nottingham-http-link-header-07-from-6.diff.html 
>> 
>> Your new explanation on @rev in HTML4 states:
>> 
>>> some hold that rev reverses	
>>> the direction of the link, while others that it reverses the	
>>> semantics of the relation itself
>> 
>> The HTML 4.01 Recommendation defines @rel as:
>> 
>> 	"the relationship from the current document to
>> 	 the anchor specified by the href attribute"
>> 	<http://www.w3.org/TR/html4/struct/links.html#adef-rel>
>> 
>> And @rev as:
>> 
>> 	"a reverse link from the anchor specified by the
>> 	 href attribute to the current document"
>> 	<http://www.w3.org/TR/html4/struct/links.html#adef-rev>
>> 
>> Further it illustrates this with an example (linked to from the @rev
>> definition) showing them both in use, stating that the following code in
>> Document A:
>> 
>> 	<LINK href="docB" rel="foo">
>> 
>> has "exactly the same meaning" as the following code in Document B:
>> 
>> 	<LINK href="docA" rev="foo">
>> 
>> The earlier 4.0 Recommendation has word-for-word identical definitions
>> and examples. 3.2 is similar <http://www.w3.org/TR/REC-html32#link>.
>> 
>> I don't doubt that some people are confused by @rev. (If you look hard
>> enough, you can find people confused about almost anything.) But given
>> that all the relevant recommendations are quite clear in stating that
>> @rev reverses the *direction* of the link, it seems disingenuous to
>> present them as two equally valid interpretations of the definition of
>> @rev.
>> 
>> I'd suggest changing the wording to something like:
>> 
>> 	while rev is defined to reverse the direction of
>> 	the link, some have implemented it as if it reversed
>> 	the semantics of the link type
>> 
>> Though, that having been said, although I've seen a handful of examples
>> where people have mistakenly used @rev instead of @rel, either through
>> ignorance or the slip of a finger, I can't remember seeing any which
>> *rely* on the mistaken interpretation of it reversing the semantics of
>> the link type. For example, I've never seen a page which used, say,
>> rel="author" to link to the author and rev="author" to link to people
>> who did not contribute to the document.
>> 
>> PS: in case you're not aware of it, I've implemented a parser for HTTP
>> Link headers in Perl, and am in general a big fan of them.
>> 
>> http://search.cpan.org/~tobyink/HTTP-Link-Parser/lib/HTTP/Link/Parser.pm

>> 
>> -- 
>> Toby A Inkster
>> <mailto:mail@tobyinkster.co.uk>
>> <http://tobyinkster.co.uk>
>> 
> 
> 
> --
> Mark Nottingham     http://www.mnot.net/

> 
> 
Received on Tuesday, 29 December 2009 23:36:24 UTC

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