Stability of valid IDN labels

Mark Davis mark.davis at
Sat Apr 19 00:25:09 CEST 2008

What I'm talking about is *syntactic* validity. Of course what a URL
containing a label points to could change or disappear.


On Fri, Apr 18, 2008 at 2:34 PM, Eric Brunner-Williams <
ebw at> wrote:

> Mark,
> The requirements for labels arises somewhere, and I suspect that for the
> IETF's IDN activities, past and present, the author of that requirement is,
> at in part, ICANN, in the broad, constituency sense, not the almost
> uniformly non-technical members of staff employed by ICANN.
> If that is the origin of the requirement for stability, in my opinion,
> your requirement that a label be "valid (or invalid) forever" is stronger
> than the requirement originating from ICANN for IDNs.
> Please consider the 3166 code points in the zone file that the IANA
> directly manages. These are not "valid (or invalid) forever", where there
> was an alpha-two label "SU" there are now several distinct alpha-two labels
> labels. The ISO3166/MA publishes newsletters with occasional changes to one
> or more code points, which are eventually reflected in the validity, or
> invalidity, of labels in the root zone. Now it is true that there is no
> change in the [A-Z][a-z][0-9][-,.] and length restrictions on labels formed
> from ASCII characters, but that is a truth about a production rule, not a
> truth about any particular label.
> Perhaps this is a distinction without difference, as per-character
> determinations of label validity may be a production rule for a class of
> labels with only one member.
> If so, again in my opinion, the ICANN requirement for stability does not
> approach the semantics of "forever", there simply is no planning process in
> ICANN for any requirement that is as fixed in its intent as that of the
> authors of the BCD series of standards, or the ASCII series of standards,
> for a present work that cannot, and also need not, be modified within a few
> short years, as we are attempting now, on the work of the earlier IETF IDN
> WG.
> The difference between "for as long as we think this work is used" and
> "forever" may allow CONTEXT rules to become more restrictive.
> Eric

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