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Re: NEW ISSUE: repeating non-list-type-headers

From: Adrien de Croy <adrien@qbik.com>
Date: Wed, 21 Nov 2007 00:29:33 +1300
Message-ID: <4742C51D.1010609@qbik.com>
To: Julian Reschke <julian.reschke@gmx.de>
CC: Bjoern Hoehrmann <derhoermi@gmx.net>, HTTP Working Group <ietf-http-wg@w3.org>



Julian Reschke wrote:
>
> Unless there's another place in the spec making statements about 
> repeating headers (is there?), both
>
>   MAY do X, iff Y
>
> and
>
>   MUST NOT do X, unless Y
>
> are equivalent.
>
neither of these constructs are that great - having read this one being 
thrashed out in other conversations.  I think we need to look into what 
the goal is.  Clarity surely?

there are complications as previously discussed around use of the word 
"MAY", in the strict (RFC defined) sense, vs the everyday sense

Personally I feel the first form is more correct, since to derive the 
same meaning from the second form, you have to implicitly convert a 
conditional non-denial into an optional conditional permission.  They 
aren't 100% the same thing. Lack of denial is not necessarily a grant of 
permission.  There may be other factors.

If you want real clarity, we may need to say something more convoluted, 
i.e. repetitive, such as

MAY do X but only if Y. If not Y then MUST NOT do X

It's redundant etc, but it drums in that doing X is _optional_, but only 
on condition that Y is met, otherwise X is not permitted.

Use of the word "only" (which is in the spec in a few places) can make 
things a bit fuzzy.  Adding "but" can help there in terms of general 
legibility.


-- 
Adrien de Croy - WinGate Proxy Server - http://www.wingate.com
Received on Tuesday, 20 November 2007 11:31:51 GMT

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