Vint Cerf wrote:
setting aside interpretation and semantics for a moment, would there
be utility in maintaining tables for each instance of Unicode?
Yes, because developers will have different versions of Unicode
available to them. It would also help developers to migrate by seeing
what has changed between versions.
On Tue, Jun 7, 2011 at 10:45 PM, Paul Hoffman <paul(_dot_)hoffman(_at_)vpnc(_dot_)org
On Jun 7, 2011, at 6:24 PM, John C Klensin wrote:
> I think this is an improvement but there is one issue about
> which we have slightly different impressions. I hope the
> difference can be resolved without needing yet more tedious
> arguments about documentation. Indeed, if such arguments are
> required, I'd prefer that we just forget about it.
> Anyway, your comments above about "most current version" imply
> to me that IANA should keep derived property tables for the most
> current version only. My expectation when 5982 was completed
> was that IANA was expected to keep derived property tables,
> clearly identified by version, for each and every Unicode
> version from 5.2 forward. In other words, the tables for the
> [most] current version would be added to, not replace, whatever
> previous version tables were around. The reasons for this, in
> terms of systems and implementations in various stages of
> development, implementation, and deployment, seem obvious... but
> maybe it was too obvious to some of us at the time to get the
> wording exactly right.
While your interpretation could be one thing we might have meant,
it is not what is reflected in the RFC or the registry. RFC 5892 says:
5.1. IDNA-Derived Property Value Registry
IANA has created a registry with the derived properties for the
versions of Unicode released after (and including) version 5.2. The
derived property value is to be calculated in cooperation with a
designated expert [RFC5226] according to the specifications in
Sections 2 and 3 and not by copying the non-normative table found in
If non-backward-compatible changes or other problems arise
creation or designated expert review of the table of derived
values, they should be flagged for the IESG. Changes to the rules
(as specified in Sections 2 and 3), including BackwardCompatible
(Section 2.7) (a set that is at release of this document is empty)
require IETF Review, as described in RFC 5226 [RFC5226].
Note that every reference to the registry is singular. Also, the
doesn't mention "5.2" at all.
If the registry definition does not talk about keeping versions,
and the registry itself doesn't look like it tried, it may be
implausible to think that IANA would just start to do so in some
future. To me, "a registry" means a single registry.
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