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

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 20 Nov 2007 13:36:44 +0100
Message-ID: <4742D4DC.3000505@gmx.de>
To: Bjoern Hoehrmann <derhoermi@gmx.net>
CC: Frank Ellermann <hmdmhdfmhdjmzdtjmzdtzktdkztdjz@gmail.com>, ietf-http-wg@w3.org

Bjoern Hoehrmann wrote:
> * Frank Ellermann wrote:
>> Bjoern Hoehrmann wrote:
>>
>>> You are turning "Messages may X iff Y" into "Messages must not X unless Y"
>> You've lost me here, isn't that logically equivalent ?  If it is equivalent
>> Julian's version is clearer.  If it is not I likely miss the point.
> 
> Julian's version allows using the same name more than once through a
> double negative under the assumption that MAY is the antonym of MUST
> NOT. I would not make this assumption, and I think double negatives
> are generally more difficult to understand than positive statements.

No, "MUST NOT" is not an antonym for "MAY".

However

	MAY do X if and only if Y

means the same as

	MUST NOT do X unless Y

I think the latter was clearer as it communicates that the default is 
that repeating header names are not allowed (that is, headers using list 
syntax being the exception).

> If you want clearer text you would have to split the statements up
> and say: list-valued headers may occur more than once, other headers
> must not occur more than once.

Agreed.

BR, Julian
Received on Tuesday, 20 November 2007 12:37:13 GMT

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