UNASSIGNED, DISALLOWED, PVALID, and MAYBE (was: Re: Unicode 5.2 -> 6.0)

John C Klensin klensin at jck.com
Fri Oct 15 00:51:22 CEST 2010

--On Thursday, October 14, 2010 16:47 -0400 Eric
Brunner-Williams <ebw at abenaki.wabanaki.net> wrote:

> I think gTLD operators (and their respective technical
> services providers, where distinct) should be advised* that
> allowing any of the version delta characters before
> consultations** is premature.


--On Thursday, October 14, 2010 16:51 -0400 Andrew Sullivan
<ajs at shinkuro.com> wrote:

> For
> if this is going to be a regular problem in future, it seems
> like one would be better to have some new class like
> PROBABLY-PVALID where characters we're not sure about live for
> a couple releases of the Unicode tables. 


--On Thursday, October 14, 2010 14:34 -0700 Mark Davis ☕
<mark at macchiato.com> wrote:

> As far as an implementation is concerned, UNASSIGNED ==

Folks, this note is more about procedures than about substance,

-- The original proposals for what evolved into IDNA2008
	contained a pair of categories, then called MAYBE YES
	and MAYBE NO, that were intended as a kind of purgatory
	for scripts and languages about which we weren't
	confident that we had sufficient information, weren't
	confident that anyone actually understood how to use
	correctly for domain names, for which we thought more
	consultation was needed, and just as a place to put
	newly-added characters while they matured enough in use
	elsewhere to make rational and informed decisions about
	IDN use.  Those categories were dropped during the
	period just before the WG was formed but were documented
	in I-Ds during that period.  If my recollection is
	correct no one made a serious proposal during the WG's
	lifetime to put them back in.
	Even though I have some regrets every time an issue like
	this comes up (either in practice or in theory) I
	personally think we should treat that decision as closed
	unless someone is willing to make a serious proposal (by
	definition, in the form of an I-D) to open IDNA and put
	the categories back in... and then see if they can get
	any traction for the idea given that the community
	clearly wants to move forward with IDNs and not have to
	go through more uncertainty while we work on new
	category definitions and the associated tables.
-- The WG discussed, at great length, the questions of
	whether UNASSIGNED and DISALLOWED were different in
	practice and whether DISALLOWED -> PVALID transitions
	should be treated differently from PVALID -> DISALLOWED
	transitions.  The first conclusion was pretty clearly
	that UNASSIGNED was different from DISALLOWED because
	implementations, registries, and would-be registrants
	needed to assume that UNASSIGNED code points might or
	would ultimately be assigned while DISALLOWED ones were
	expected to be stable in that state.  And the second
	conclusion was neither change was acceptable except in
	truly exceptional situations.
	Again, my personal preference is that we not reopen
	either decision because I don't think the advantages of
	doing so come even close to outweighing the
	disadvantages of destabilizing the IDNA2008 definition.
	If someone has a different opinion for which they are
	prepared to argue, please generate an I-D with a
	proposal.  But, at least IMO, we aren't going to make
	progress by wishing that the WG's conclusions were other
	than they actually were.

It is not clear to me that the above leads to any particular
conclusion about what we should do about these three characters.
But perhaps it could be helpful in focusing the discussion.


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