> On 08/05/2013 08:33, Ned Freed wrote: > >> On 08/05/2013 03:28, John C Klensin wrote: > >> ... > >>>> I'll also point out that this has diddley-squat to do with > >>>> formal verification processes. Again as Mark Anrdrews points > >>>> out, we deployed something with a restriction that > >>>> subsequently turned out to be unnecessary, and now we're stuck > >>>> with it. Indeed, had formal verification processes been > >>>> properly used, they would have flagged any attempt to change > >>>> this as breaking interoperability. > >>> Also agreed. > > > >> To be clear, I'm no fan of formal verification either, but this > >> *is* a case where the IETF's lapse in formality has come back to > >> bite, and the Postel principle would have helped. Also, given the > >> original subject of the thread, I don't see how language editing > >> could have made any difference. > > > > Reread the notes about the history behind this in this thread. You haven't even > > come close to making a case that formal verification of the standards would > > have prevented this from happening. > 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. Which is relevant to the present situation... how exactly? And in any case, the relevant URI standard incorporates the ABNF from RFC 2373, but doesn't state whether or not it also inherits restrictions specified in prose in that specification, which is where the restriction in RFC 2821 originated. > 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.) Except that wasn't the problem. The ABNF in the email standards is consistent with what the other standards said when RFC 2821 was published. And once that happened the die was cast as far as email usage was concerned. The fact that the other standards later decided to loosen the rules in this regard is what caused the inconsistency. If you want to blame something, it has to be either the initial decision to limit use of :: or the subsequent decision to remove that limit. And for increased formalism to have helped it would have to have prevented one of those from happening. I supose that's possible, but I certainly don't see it as inevitable. Ned