SHOULD vs MUST (was Re: Review of draft-ietf-geopriv-http-location-delivery-07)

Lawrence Conroy <lconroy@insensate.co.uk> Sat, 21 June 2008 13:31 UTC

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From: Lawrence Conroy <lconroy@insensate.co.uk>
To: Eric Rescorla <ekr@networkresonance.com>
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Subject: SHOULD vs MUST (was Re: Review of draft-ietf-geopriv-http-location-delivery-07)
Date: Sat, 21 Jun 2008 14:31:03 +0100
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Hi Eric, folks,
  [renamed for this specific point, and CC list trimmed]

I am puzzled by this point in your review.
I suspect that other potential authors will be too.
To me, the last sentence is exactly right:
the SHOULD means "do this unless...",
and the last phrase covers the "unless".

I had read 2119 to mean that a MUST was unconditional
- do this or be non-complaint.
Do you believe that MUST can have an "unless" clause?
Doesn't this mean that any SHOULD with an explicit "unless" will
need to be changed into a MUST - could you expand on this, please?

all the best,
   Lawrence

On 20 Jun 2008, at 20:59, Eric Rescorla wrote:
>>   The LIS MUST implement the server
>>   authentication method described in [RFC2818]. When TLS is used,
>>   the Device SHOULD fail a request if server authentication fails,
>>   except in the event of an emergency.
>>
>> Does that address your concerns?
> Why did this become a SHOULD when it was a MUST?

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