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

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Tue, 20 Nov 2007 14:07:46 +0100
To: Julian Reschke <julian.reschke@gmx.de>
Cc: www-archive@w3.org
Message-ID: <4el5k3t1lf9rnf3rjo57curul65cdojh86@hive.bjoern.hoehrmann.de>

* Julian Reschke wrote:
>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

Neither form is particularily brilliant, but you can infer in the first
version that there is nothing else to learn about the "if Y" case, while
that is not clear with the second version. If you add something like so:

  * MUST NOT do X unless Y, but SHOULD NOT do X even if Y
  * MAY do X if and only if Y, but SHOULD NOT do X even if Y

I would read this as

  * SHOULD NOT do X and MUST NOT do X unless Y
  * MAY do X if Y and SHOULD NOT do X if Y and MUST NOT do X unless Y

The first version makes sense, while the second one is contradictory.
Only the may iff-version immediately answers "Well what /if/ Y". You
admitted as much when saying "Unless there's another place in the spec
making statements about repeating headers ..." :-)
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
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Received on Tuesday, 20 November 2007 13:07:54 GMT

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