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INTERNET-DRAFT                                John C. Klensin
June 19, 2002
Expires December 2002

                           Internationalizing the DNS -- A New Class

Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026 except that the right to produce
derivative works is not granted.  The above restriction will be removed
by the author in a subsequent version of this draft; the author should
be contacted for permission if needed sooner.

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups.  Note that other
groups may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at

The list of Internet-Draft Shadow Directories can be accessed at

0. Abstract

Several mechanisms have been proposed for placing multilingual names
(more properly, names normally written in non-ASCII character sets)
into the DNS or addressing the need for multilingual access to the
Internet in other ways.  Most of them involve, to one extent or
another, workarounds to the current system.  This document proposes a
"go back and fix it" approach, replacing the "IN" Class in the DNS with
one that is not limited to ASCII from its initial definitions.  Some of
the deployment issues, politics, and other drawbacks are also briefly

The draft is being republished at this time, with a few corrections
and some new text, because it is complementary to a recent draft by
Ted Hardie [Hardie-Class] and because it may be part of the foundation
for a different DNS internationalization proposal.  The author is no
longer convinced, if he ever was, that this proposal is adequate for
DNS internationalization, at least without considerable enhancement.

A mailing list has been initiated for discussion of this draft, its
successors, and closely-related issues in the Internationalization
context at ietf-i18n-dns-newclass@imc.org.  To subscribe to the
mailing list, send a message to ietf-i18n-dns-newclass-request@imc.org
with the single word "subscribe" (without the quotes) in the body of
the message. To unsubscribe from the list, use that same address with
the single word "unsubscribe" in the body of the message.  Issues
related to the relationship of the model proposed here to general
issues of multilingual access to the DNS should be raised in the IETF
IDN WG working group, see

Table of Contents

1. Introduction and Context
2. Overview of the Proposal
3. Technical alternatives and the deployment and transition nightmare
        3.1 Preparation and comparison of names
        3.2 Registrations in both places
        3.3 Search rules and search failures
        3.4 A "new class" solution versus an "edns/utf-8" one.
        3.5 A "new class" approach versus an "ACE" one.
        3.6 A "new class" approach versus a "directory" one.
        3.7 Another look at legacy applications
        3.8  New Classes and IPv6 Transition
4. Bringing RR types forward
5. Pushing into layers eight through ten
        5.1 The root server question
        5.2 Other administrative challenges
        5.3 Thinking about deployment
6.  Summary
7. References
        7.1 Normative references
        7.2 Non-normative references
8. Acknowledgements
9. Author's address

1. Introduction and Context

There have been a large number of proposals, both inside and outside
the IETF, for getting multilingual (or "internationalized") access to
the DNS.  With the exception of a few proposals that focus on doing
the work in a separate system that permits searching (see [Klen-role,
Klen-search, Meal-SLS], and others) and several suggested or deployed
commercial products), all involve inserting the names into the
existing DNS structure.  This would be done either by using special
conventions and preprocessing of international characters into an
ASCII representation or by using a character set repertorie that
includes more than ASCII [ASCII] and some encoding to place characters
from that repertorie into the system.

To a considerable degree, while the objective is multilingual access
to names (i.e., access from multiple languages), very few of the
proposals address languages at all.  For a number of good reasons,
which are adequately discussed elsewhere, discussion has focused on
access to the system with characters other than those that appear in
ASCII and, in particular, characters drawn from ISO 10646 [IS10646].
This document, too, addresses characters, not languages, and
"non-ASCII", "international", "multinational", and, following ISO's
example, "universal character set" ("UCS") terminology are used
interchangably below.  When "multilingual" is used, it refers to the
languages in which words or names appear, not what is placed into the

When the DNS was designed, it was anticipated that there might be
future extension through the use of "Classes".  All common current uses
on the public Internet use the "IN" class.  Two additional classes are
known to have been defined and used: one for the old Chaosnet protocols
and one for Hesiod-based protocols.  Potential extensions via the Class
mechanisms may have been one of the reasons that DNS labels and other
fields were defined as binary, rather than ASCII, forms.

Applications using the IN Class have historically assumed labels
limited to seven-bit ASCII characters and, more specifically, a
"protocol element" character set derived from ARPANET "hostname" rules
(see [Klen-3071]).  This document explores the question of what the
DNS, and "DNS names", might have looked like had we been designing it
today.  I.e., it assumes that multilingual usage would be a priority
but that current technology and existing standards are available.  It
also outlines the issues associated with a transition mechanism.

The proposal is radical in the sense that it implies a major
restructuring of DNS usage and, indeed, of the Internet, to make the
DNS seamlessly capable of working with multinational (or, more
properly, "universal") character sets.  Such a restructuring is, and
should be, quite frightening.  It is worth considering only if the
long-term risks and problems of other proposals are severe enough to
justify a radical approach.  It is the working hypothesis of this
document that they are.  At a relatively technical level, this would
require changing every DNS resolver and server, and application that
accesses either, on the Internet that wished to use non-ASCII names.
Legacy (unconverted) systems would be at a significant disadvantage in
referencing new names (some of which might use only a subset of ASCII
characters but might still not be registered in the older Class), just
as legacy systems were during the transition between Hostnames and the
DNS.  There are also a number of problems, such as the weaknesses of
the DNS as a directory system, which it does not solve (see section
3.6, below).

It also does not significantly address the very complex issues of
normalization, mapping, and canonicalization that are needed for the
use of Unicode (or, in all likelihood, with any future alternate
approach to a universal character set).  The key issues in that area
are addressed in the existing "stringprep" [stringprep] proposal and
its profiles.  See section 3.1 for further discussion on this issue.

2. Overview of the Proposal

Suppose we introduce a new Class (let's call it UC for "universal
characters" just as a placeholder, but I hope that isn't what we would
choose), which is just like IN (i.e., inherits its RR definitions, but
see below), except:

   * Labels and all fields containing text are defined as IS 10646
   characters, coded in UTF-8 (or, in principle, some other _single_
   system, i.e., we do not permit multiple character sets in the

   * A new RR is introduced that maps a new-type label (in the new
   class) into a restricted-ASCII (traditional) label.   The intent is
   that the resolver then looks up the restricted-ASCII label in the IN
   class and proceeds as usual.  Probably it would need to have
   "nothing else there" restrictions like CNAME, but (to put it mildly)
   I haven't thought that through. An alternative would be to adopt a
   search rule strategy, looking first with Qclass=UC and then
   Qclass=IN.  The new RR might not be needed if one adopted a search
   rule strategy, or strong administrative rules requiring that all
   Class IN records be transposed into Class UC (see below).

   * A second new RR is introduced that indicates that a delegated
   subdomain of a zone in Class=UC is in Class=IN, and not in
   Class=UC.  This would be a variation on "NS", but would specify
   both the Class and the name associated with the relevant name
   server. (Note that a references from Class=IN to Class=UC makes no
   sense and mechanisms for it should not be provided.)

It is not clear at this time whether both the second and third
"crossreference" RRs would be necessary, but almost certainly at least
one would be.

This brief outline obviously leaves out many critical details which
would need to be worked out, only some of which are explored in this
draft of the document.

3. Technical alternatives and the deployment and transition nightmare

A "new class" proposal would obviously not be easy to deploy, but,
realistically, neither are any of the other ideas if the definition
of deployment involves users having access to Internet names drawn
from a broad range of languages.  It would cleanly separate
"international character set" name spaces from the "ASCII" one --
i.e., "old" clients and systems would never see the non-ASCII types.
In the international name space, English, and the character code
points used to represent it, becomes just one of many such languages
and their corresponding character code points.  It might even let us
fix a few other things along the line, as long as they were
sufficiently straightforward to not create significant delays.  E.g.,
there are several RR types in the current Class that are either
obsolete or have never been widely used, and we might be able to
eliminate them by not carrying them forward.

While other transition models are possible, the cleanest one would be
to conclude that the new Class was intended, over time, to simply
obsolete and replace Class=IN.  If registrations in Class=IN were
transferred into (or explicitly referenced from) the new class (or a
"search rule" system was employed), then the transition model would be
very similar to that of the hosttable-> DNS transition.  In particular,
"old" clients and systems would see a smaller and smaller fraction of
the Internet until they converted and we would expect some user-level
tools to arise to work around slow conversions.

3.1 Preparation and comparison of names

Subsets of ASCII, or character codes whose character repertoires are
themselves subsets of ASCII, have long been the character repertoire
of choice for the protocol elements of protocols that use characters
in such elements.  While some of the reasons for this --arguably
including the decision to use characters from a Roman- (Latin-) based
alphabet-- are simply historical, ASCII has the advantages of
containing a very small (by world averages) set of characters, of
permitting an extremely easy case-mapping algorithm (and case-mapping
is important in Roman-based and several other languages), of requiring
no "composed" characters, and of raising no significant issues with
canonicalization, collation, or identity-matching.

To varying degrees, as soon as the character repertoire moves beyond
the requirements of ASCII, comparison issues intrude: it is necessary
for a DNS server to determine whether the name specified in a query
matches the name that appears in its tables for a domain.  And that, in
turn, requires either that strict rules be applied to how names are
stored and how queries are presented or that the server be able to
interpret a somewhat-ambiguous (or "fuzzy") query.  The latter option
is infeasible given the design of DNS servers (although non-DNS systems
might permit it -- see section 3.6 and [klen-role]).  The former has
been the focus on the "nameprep" efforts within the IDN Working Group.

In general, the mechanisms and rules being developed as part of the
"nameprep" effort would need to be applied to a "new class" system,
just as they would need to be applied to "edns/UTF-8" or "ACE"
systems.  However, one potential advantage of a "new class" approach,
and possibly of an EDNS-based one, is that it would be possible to
move some of the comparison and mapping functions out of a pre-query
sequence on the client and onto the server.  That, in turn, would
permit case mapping and matching for non-ASCII texts to be handled in
a way much more similar to ASCII text today (e.g., storage of mixed
case materials in zone files with queries in any case and return of
the registrant-desired form).  To the extent that centralizing complex
functions on the servers improves reliability, it would also have that

3.2 Registrations in both places

A "multilingual" name registrant could choose whether to register the
multilingual name exclusively or whether to register ASCII-based names
as well (giving most of the useful properties of the two-sided business
card analogies).  Such ASCII-based names could be registered in the new
class; they could presumably also be registered in the old class for
compatibility with legacy systems.  We would not expect reverse
mappings to work from IN-space to UC-space; PTR lookups in Class IN
would yield ASCII names; PTR lookups in Class UC would yield IS 10646-
based names.  And we would expect all other fields that contain text to
contain IS 10646-based text, not just ASCII.  Finally, moving critical
portions of the normalization and comparison work to the server might
make it easier to deal with some of the issues of in superimposing
internationalized names on DNNSec a bit easier, or at least possible
to have better-behaved.

There is probably no practical way to automate dual registrations in
the general case (keeping in mind that naming and identification issues
that exist near the root also exist deep in the DNS tree), so decisions
about legacy registrations would need to be administrative and policy
based.  See section 5.  Search rules (see next section) might be an
acceptable substitute for dual registrations, but have their own

3.3 Search rules and search failures

Unless all relevant records in Class=IN are copied into Class=UC and
the two are kept synchronized (very difficult if not impossible to
maintain), there will be a requirement for searching from the newer
class to the older one.  That requirement could, in principle, be kept
in the servers and off the network by providing for new servers to
automaticaly search in Class=IN if nothing is found in Class=UC without
intervening interactions with the resolver. This could introduce
significant complexity and a number of special cases into the server
and might or might not be wise.  Since a new Class causes
multiplicative effects on the number of probes potentially required to
complete a search, minimizing the number of similar RR types in the new
Class becomes technically advantageous as well as aesthetically so (see
section 4).

The potential need to make queries in both Class=UC and Class=IN for a
given user-supplied name provides an immediate, and strong, reason why
the fundamental domain hierarchy structure of both Classes should be
identical, even if the servers are not.  If identity of servers is not
practical (it probably would not be significantly below the top level,
if there), the portion of the Class=UC tree that shared names with the
Class=IN tree would need to be identically structured.  Almost by
definition, as non-ASCII non-terminal nodes are introduced into the
Class=UC tree, that tree would diverge from, or become a superset of,
the Class=IN one.  The alternatives would, at best, be hopelessly
confusing to users.

But, if searching mechanisms from Class=UC to Class=IN will be in
regular use, it is tempting to rely on those mechanisms rather than
doing any forward copying of data.  This would increase overhead in
comparison to having all information copied into the UC class as
early as possible, but the range of alternatives needs to be studied
carefully, especially with regard to domain trees that contain
non-ASCII names and UC-capable servers at some nodes and only ASCII
names and legacy servers at others.  The special, cross-Class NS RR
suggested above would help with such trees, but some searching
strategies might make strict bottom-to-top conversion of subtrees
(rather than level-skipping) very valuable if not necessary.

Having two classes also raises issues for which the answers seem
obvious, but decisions must be made and made explicit.  For example, it
seems clear that one should search
   ((QClass=UC, Qtype=MX, ...)
    (QClass=UC, Qtype=A6, ...)
    (QClass=IN, Qtype=MX, ...)
But, at least in theory, a case could be made for looking for MX RRs in
"IN" before looking for address records in "UC".

3.4 A "new class" solution versus an "edns/utf-8" one.

Some of the proposals before the IDN working group (and elsewhere)
depend on the use of "extensible DNS" ("edns") facilities to permit
extended labels and the use of UTF-8 encoding in them.  Proponents
point out that edns is extremely useful for IPv6 and DNNSEC, so will
probably deploy quickly anyway; its use for non-ASCII DNS labels would
both benefit from and reinforce those deployment pressures. One of the
barriers to the deployment and heavy use of extensible DNS [RFC2671] is
that its use in the current, Class=IN, environment depends somewhat on
updating of intermediate servers.  In other words, an updated client
and updated primary server may not be able to properly interoperate
because caches or secondary servers may still be running older code.
In principle, and probably in practice, this is not an issue with a new
Class: absent serious errors of configuration, name servers delegations
and caches for the new class would be only to servers supporting that

3.5 A "new class" approach versus an "ACE" one.

Several of the proposals in the IDN working group (and elsewhere)
depend on encoding ISO 10646 characters into an ASCII-compatible format
(an ASCII-compatible encoding, hence "ACE") so that the names, however
ugly, would survive passage into applications that have intrinsic
seven-bit limitations.  That group of applications is somewhat more
diverse than what is usually thought of as "internet applications".
For example, X.509 certificates are used in SSL and assume seven-bit
characters.  The ACE codings would work with those applications,
although they would look nothing like the graphic characters of the
original character set and language.

While this document has assumed using the UTF-8 encoding of IS 10646
directly in the names and labels of the UC class, UTF-8 is just
another encoding and not an especially efficient one.  There may be
applications-based arguments for using an ASCII, or ASCII-compatible,
encoding to represent character codes in the new Class as well.
However, since all codes in the new Class would be using the same
system, one could devise a system that did not require a switching or
labeling mechanism to identify the use of the coding system versus the
appearance of codes in the ASCII range intended to be interpreted as
ASCII.  I.e., prefixes or suffixes might become unnecessary and it
might be possible to use higher-density encodings, such as MIME's
base64, or a serious compression algorithm applied to UCS-2 or UCS-4
(or the similar UTF-16 or UTF-32), rather than UTF-8 or those
encodings more commonly suggested as ACE mechanisms.

3.6 A "new class" approach versus a "directory" one.

Many of the issues raised in [Klen-role] are not addressed by this
proposal.  Neither it, nor any other DNS-based solution, would turn
the DNS into a searchable directory ([klen-search] does provide a
model for a searchable directory, but the work is not done in the
DNS).  Nor can they address imprecise matching, keyword matching,
nearest applicable server location, searching on the content of data
fields, and so on.  This proposal does provide a plausible solution
to reverse-mapping problems, deployment, and has known scaling
properties: all areas where the notions outlined in [klen-role] are
weaker.  It would probably be somewhat faster than a directory
approach layered on the DNS, since there would be no requirement for
a two-stage lookup process.  But, ultimately, the two proposals are
complementary: There is a strong applications case for introducing a
directory layer.  While the directory layer could be used to support
multilingual names -- treating the ASCII-based names in the DNS as
protocol elements rather than names that ought to be user visible --
it could also be used with a DNS that actually and cleanly supported
multilingual names as suggested here.

3.7 Another look at legacy applications

As suggested above, there are some applications, many with origins
outside the IETF, that cannot be easily upgraded to use of non-ASCII
(or, generally, non-seven-bit), character codes.  It is difficult to
know what to do about those applications.  If we are really serious
about converting the Internet to support applications in all
languages (which is ultimately the assumption underlying this
document), then the answer may be more clear: the overhead of dealing
with the UCS to ASCII interface ought to fall on those applications,
as an intermediate step until the protocols themselves can be
upgraded.  In other words, we might anticipate a four-stage
conversion process for those applications:

(i) Completely legacy (non-updated) code would continue to reference
    Class=IN (no other option is possible).

(ii) Applications code would be upgraded to make QClass=UC inquiries
    and to represent the UCS codes for their databases and
        presentations in some ASCII-compatible form compatible with their
        protocol definitions.  In other words, the DNS would return some
        native form variation on UCS, conversion to ASCII-compatible form
        would occur, when needed, on the applications side of the DNS

(iii) The protocols would be upgraded to international norms and usage.

(iv) The applications code would be changed to conform to the new
    protocols, eliminating the workaround of stage (ii).

If these conversions and downgrades, espeically those of step (ii),
are incorporated into the DNS, we are stuck with their overhead and
appearance forever.  That is, of course, also true of any encoding
tricks (e.g., the "ACEs" under consideration in the IETF IDN WG, e.g.,
[DUDE]) used to represent non-ASCII names in Class=IN without putting
applications at obvious risk.  And different applications, with
different constraints, may have to convert them to application-
specific formats anyway.  Somewhat different strategies, available
with the new class approach only, could eliminate the need to make
workarounds and kludges a permanent part of their systems and the
Internet infrastructure.

3.8  New Classes and IPv6 Transition

The transition to IPv6 has raised an interesting general DNS issue
because it may require that DNS servers support a dual stack
arrangement to permit access of records from resolvers based on both
IPv4 and IPv6 systems.  (This document will not attempt to fully
explain that problem and its implications.)  It is possible that, were
a new Class developed as an incremental replacement for Class=IN, it
could be used as a mechanism for handling IPv6 queries.

4. Bringing RR types forward

In principle, one could populate the UC Class with all of the types of
the IN one, possibly eliminating those that are clearly obsolete, as
mentioned above.  A narrow reading of many of the existing definitional
documents might even require this, although we can be assured that no
queries or registrations in class=UC exist today.  But it might be
interesting to evaluate the implications of taking a harder line,
partially to shorten search paths and minimize the size of zone files.
Several RR types have been added "experimentally"; it would probably be
wise to leave those for which there isn't considerable deployment and
justification behind.  We might also consider leaving AAAA RRs behind
as obsolete or redundant, since A6 is the more general of the two.
And, more radically, one might consider eliminating type A RRs, writing
IPv4 addresses in IPv6 form, e.g.,

   kakameymi.example.   UC  A6  0  ::FFFF:

and letting APIs to resolvers translate them back into IPv4 format if
needed.  By doing this, the potential need to query for A6, AAAA, and A
RRs in sequence would disappear, resulting in some performance
improvement, especially for the "not found" cases.

Of course, similar logic might apply to a lighter-weight successor of
A6, or even a variation of AAAA with a specialized high-order coding

This might raise entry barriers too much to be worthwhile, but, if
feasible (and we really believe in IPv6 deployment), it would yield a
much cleaner environment for both forward and reverse mappings.

On the other hand, eliminating other types in favor of A6 might be
advancing the technology in too many ways at once.  For example, while
the A6 RR appears to be fully general, there is so far little few real
experience on using it (or other IPv6 RRs) and none of that experience
is at large scale.  It may be wise to go somewhat cautiously into
directions that tie the new class to such less-than-complete-tested

5. Pushing into layers eight through ten

(For those who don't know, these layers have become an internal joke in
the IETF community whose exact origins are unknown to this author.  The
layers are characterized as "financial", "political", and "religious",
with some debate about the order.)

A new DNS class really would be new.  Current Internet administrative
procedures and lines of authority with regard to the DNS have assumed
that Class=IN is the only class at issue.  It is to be hoped that IETF
could identify technical criteria and other important tradeoffs but
leave the non-technical issues and resolution of policy and political
tradeoffs to ICANN and related bodies.

5.1 The root server question

The design of the DNS is such that there is no inherent reason why
root servers for a new class would need to be the same as those for
IN.  However, the same considerations for root server selection that
apply to the Class=IN root [rfc2870] would presumably apply to the
Class=UC root as well.  There would be several other administrative
and operational advantages for keeping many or all of the root servers
the same --or at least co-locating them-- as long as loads, software
availability, and similar factors permitted.

5.2 Other administrative challenges

Just as the root servers would not need to be the same, the
introduction of a new Class would, in theory, permit revisiting the
entire top-level structure and administration of the the Class=IN DNS
(e.g., there would be no requirement that the TLD names or model be
the same).  Doing so would probably be unwise if we wanted to see
this deployed in our lifetimes, but the possibility must be
identified and, at least briefly, considered.

5.3 Thinking about deployment

It is clear that, like any other multilingual approach, software
supporting a new DNS class would deploy much more quickly in areas
which clearly need it than in areas that perceive they do not.  The
requirement for communication with, and access to sites in, non-
English-speaking areas would tend to drive deployment in other areas
with this and many other approaches.  The so-called "ACE" approaches
within Class=IN (and perhaps some others) using the IN Class would
permit non-updated sites to see multilingual names in their ugly
encoded forms; it is possible that would actually act as a
disincentive to updating and conversion since the names would still
be somewhat visible; this proposal would not make multilingual names
available in any form to legacy systems.  On the other hand, some
have argued that the use of ACE-type systems in the current Class
would make the full horrors of kludgy and insufficient implementation
of multilingual names visible to all, encouraging the deployment of
either the type of system outlined here, or a search-based one, or

Whatever thinking is done about deployment tradeoffs should consider
Internet growth rates, especially in non-English-speaking areas.
Whatever solution is adopted, we will need to live with it for a long
time.  If no old systems are ever converted, but new ones installed
after a particular date have updated software installed, and
"doubling every year" behavior continues, then the legacy base
represents half of the Internet a year later, a quarter of the
installed base a year after that, and so on.  So, a sufficiently
important change, incorporated into relevant shipping software, has a
very large percentage impact even if there is no actual updating of
systems.  This is something to keep in mind, especially if the
alternatives are overhead-laden kludges that we will need to support

6.  Summary

<<To be supplied in the next draft>>

7. References

7.1 Normative references

[ASCII] American National Standards Institute (formerly United States of
America Standards Institute), X3.4, 1968, "USA Code for Information
Interchange". ANSI X3.4-1968 has been replaced by newer versions with
slight modifications, but the 1968 version remains definitive for the

[IS10646] ISO/IEC 10646-1:2000 Information technology -- Universal
Multiple-Octet Coded Character Set (UCS) -- Part 1: Architecture and
Basic Multilingual Plane and ISO/IEC 10646-2:2001 Information
technology -- Universal Multiple-Octet Coded Character Set (UCS) --
Part 2: Supplementary Planes.

7.2 Non-normative references

[RFC2671] Extension Mechanisms for DNS (EDNS0). P. Vixie. August 1999.

[RFC2870] Root Name Server Operational Requirements. R. Bush, D.
Karrenberg, M. Kosters, R. Plzak. June 2000

[hardie-class] Hardie, T., "A DNS RR for Pointers to RRs outside
class IN", work in progress,

[klen-3071] Klensin, J., "Reflections on the DNS, RFC 1591, and
Categories of Domains", RFC 3071, February 2001.

[klen-role] Klensin, J., "Role of the Domain Name System", work in

[klen-search] Klensin, J., "A Search-based access model for the DNS",
work in progress

[meal-sls] Mealling, M. and L. Daigle, "Service Lookup System (SLS)",
work in progress.

[stringprep] Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ('stringprep')", work in progress,

8. Acknowledgements

Rob Austein and Randy Bush made very significant contributions to the
thinking and some of the text that went into early versions of this
draft through a series of email discussions.  Others, including Marc
Blanchet, Vint Cerf, Kilnam Chon (with apologies for writing his name
in ASCII characters rather than Korean ones), Patrik Faltstrom (with
apologies for the ASCII transposition), Paul Hoffman, David Lawrence,
and Zita Wenzel have made suggestions or challenged some of the ideas
in their embryonic form, leading to clarifications and clearer
thinking.  More recent discussions with Erik Nordmark, Ted Hardie, and
Dan Oscarsson, and observation of many discussions on the IDN WG list
contributed to the changes in draft 02.  Patrik Faltstrom first
pointed out the possible IPv6 implications of a new class approach.
The author, of course, bears ultimate responsibility for the ideas as

9. Author's address

John C Klensin
1770 Massachusetts Ave, #322
Cambridge, MA 02140

Expires December 2002

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