Hi - > From: "Brian E Carpenter" <brian.e.carpenter@xxxxxxxxx> > To: "Ned Freed" <ned.freed@xxxxxxxxxxx> > Cc: "John C Klensin" <john-ietf@xxxxxxx>; <yaronf.ietf@xxxxxxxxx>; <ietf@xxxxxxxx> > Sent: Tuesday, May 07, 2013 2:19 PM > Subject: Re: Language editing ... > You are correct if only considering the mail standards. I suspect > that a serious attempt at formal verification would have thrown > up an inconsistency between the set of mail-related standards and > the URI standard. However, I think the underlying problem here is > that we ended up defining the text representation of IPv6 addresses > in three different places, rather than having a single normative > source. (ABNF in the mail standards, ABNF in the URI standard, > and English in ipv6/6man standards.) > > > (Formal verification of implementation > > compliance to the standards would of course have prevented Apple's client bug, > > but that's a very different thing.) > > > > You are, however, correct that this has nothing to do with specification > > editing. > > > > Ned I'm not so sure about that. To me this seems to be a case of inappropriate use of MUST. First a reminder from RFC 2119: In particular, they MUST only be used where it is actually required for interoperation or to limit behavior which has potential for causing harm (e.g., limiting retransmisssions) The prohibition against using :: more than once is amply motivated. Multiple occurrances would introduce ambiguities, so that prohibition clearly warrants a MUST. The prohibition against using :: for a single 0 seems to lack such an obvious syntactic / semantic motivation. Does anyone remember why this syntactic limitation was added? Randy