Re: SHOULD vs MUST (was Re: Review of draft-ietf-geopriv-http-location-delivery-07)
Dave Cridland <dave@cridland.net> Tue, 24 June 2008 17:12 UTC
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Subject: Re: SHOULD vs MUST (was Re: Review of draft-ietf-geopriv-http-location-delivery-07)
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Date: Mon, 23 Jun 2008 11:19:51 +0100
From: Dave Cridland <dave@cridland.net>
To: Lawrence Conroy <lconroy@insensate.co.uk>
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I think I'm essentially agreeing with Eric Rescorla here, but perhaps phrasing it differently may help. On Sat Jun 21 14:31:03 2008, Lawrence Conroy wrote: > I had read 2119 to mean that a MUST was unconditional > - do this or be non-complaint. That's a reasonable assessment, given RFC 2119. > Do you believe that MUST can have an "unless" clause? I think that any MUST X unless Y can essentially be rephrased as one of "MUST (X or Y)", or "MUST (X or Y); SHOULD X". Lacking context on geopriv, it sounds like one of these (and it doesn't matter which). > 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? Again, I lack context here, but if the intent is as above, then they may do. A SHOULD X unless Y essentially means "SHOULD (X or Y)" - as Eric says, this is probably not what the intent is, although in the case of TLS authentication it might be a reasonable course of action. I have to admit that if I read a "SHOULD X unless Y", given the usual English meaning, I'd read it as the same as "MUST X unless Y", but Eric's quite correct in pointing out the difference. A final point is that actually phrasing it as "MUST X or Y" is problematic since English lacks the possibility of parenthesis for precendence - hence a stronger binding, such as MUST X unless Y, is preferable. Dave. -- Dave Cridland - mailto:dave@cridland.net - xmpp:dwd@dave.cridland.net - acap://acap.dave.cridland.net/byowner/user/dwd/bookmarks/ - http://dave.cridland.net/ Infotrope Polymer - ACAP, IMAP, ESMTP, and Lemonade _______________________________________________ IETF mailing list IETF@ietf.org https://www.ietf.org/mailman/listinfo/ietf
- Review of draft-ietf-geopriv-http-location-delive… Eric Rescorla
- Re: Review of draft-ietf-geopriv-http-location-de… Hannes Tschofenig
- Re: Review of draft-ietf-geopriv-http-location-de… Eric Rescorla
- Re: Review of draft-ietf-geopriv-http-location-de… Hannes Tschofenig
- Re: Review of draft-ietf-geopriv-http-location-de… Eric Rescorla
- Re: Review of draft-ietf-geopriv-http-location-de… Eric Rescorla
- Re: [secdir] Review of draft-ietf-geopriv-http-lo… Richard Barnes
- RE: [Geopriv] [secdir] Review ofdraft-ietf-geopri… Tschofenig, Hannes (NSN - FI/Espoo)
- Re: [Geopriv] Review of draft-ietf-geopriv-http-l… Eric Rescorla
- RE: [Geopriv] Review of draft-ietf-geopriv-http-l… Tschofenig, Hannes (NSN - FI/Espoo)
- RE: Review of draft-ietf-geopriv-http-location-de… Mary Barnes
- Re: Review of draft-ietf-geopriv-http-location-de… Eric Rescorla
- Re: Review of draft-ietf-geopriv-http-location-de… TSG
- SHOULD vs MUST (was Re: Review of draft-ietf-geop… Lawrence Conroy
- Re: SHOULD vs MUST (was Re: Review of draft-ietf-… Eric Rescorla
- RE: [Geopriv] Review of draft-ietf-geopriv-http-l… Dawson, Martin
- Re: SHOULD vs MUST (was Re: Review of draft-ietf-… Dave Cridland
- Re: SHOULD vs MUST (was Re: Review of draft-ietf-… Joe Abley
- Re: SHOULD vs MUST Frank Ellermann
- Re: SHOULD vs MUST (was Re: Review of draft-ietf-… Iljitsch van Beijnum
- Re: SHOULD vs MUST Fred Baker
- Re: SHOULD vs MUST Scott Brim
- Re: SHOULD vs MUST John C Klensin
- Re: SHOULD vs MUST Fred Baker
- Re: SHOULD vs MUST Scott Brim
- Re: SHOULD vs MUST John C Klensin
- Re: SHOULD vs MUST Scott Brim
- Re: SHOULD vs MUST Dean Willis
- Re: SHOULD vs MUST Robert Sparks
- Re: SHOULD vs MUST Dave Crocker
- Re: SHOULD vs MUST Dave Cridland
- Re: SHOULD vs MUST Iljitsch van Beijnum
- SHOULD vs MUST case sensitivity Dave Crocker
- RE: SHOULD vs MUST case sensitivity Eric Gray
- Re: SHOULD vs MUST case sensitivity Julian Reschke
- Re: SHOULD vs MUST case sensitivity Keith Moore
- SHOULD vs MUST case sensitivity Dave Crocker
- RE: SHOULD vs MUST Eric Gray
- SHOULD vs MUST case sensitivity Dave Crocker
- Re: SHOULD vs MUST case sensitivity C. M. Heard
- Re: SHOULD vs MUST case sensitivity Iljitsch van Beijnum
- Re: SHOULD vs MUST case sensitivity Randy Presuhn
- Re: SHOULD vs MUST case sensitivity Dave Crocker
- Re: SHOULD vs MUST case sensitivity Dave Crocker
- Re: SHOULD vs MUST case sensitivity Randy Presuhn
- Re: SHOULD vs MUST case sensitivity Keith Moore
- Re: SHOULD vs MUST case sensitivity Dave Crocker
- RE: SHOULD vs MUST case sensitivity Eric Gray
- Re: SHOULD vs MUST case sensitivity Spencer Dawkins
- Re: SHOULD vs MUST case sensitivity Ralph Droms
- Re: SHOULD vs MUST case sensitivity Dave Crocker
- RE: SHOULD vs MUST case sensitivity Hallam-Baker, Phillip
- Re: SHOULD vs MUST case sensitivity John Levine
- RE: SHOULD vs MUST case sensitivity Hallam-Baker, Phillip
- Re: SHOULD vs MUST case sensitivity John Leslie
- RE: Review of draft-ietf-geopriv-http-location-de… Mary Barnes