Single-letter names (was: Re: Update of RFC 2606 based on the recent ICANN changes?)

William Tan dready at
Fri Jul 4 21:01:29 CEST 2008


To add to your point, one should also consider the question of
embedded semantics in a single-character label.

Alphabetic scripts such as Latin mostly represent sounds used to make
up words. While one can certainly find some legitimate
single-character words (such as the article "a" or the personal
pronoun "i") and dream up others, it would not be very convincing in
the face of your explanation #3.

On the other hand, characters in ideographic scripts such as Han are
not mere sounds or glyphs; they represent one or more concepts.
Therefore, a single-ideographic-character TLD label is certainly more
justifiable. I would even go as far as to suggest that it is essential
in many cases. For example, "è" (U+ 732B) in both Simplified Chinese
and Japanese means "cat" as in English, not the abbreviation for
Catalan nor the UNIX command. The reverse translation of "cat" yields
the exact character in Simplified Chinese, though in Japanese
sometimes the Hiragana sequence "¤Í¤³" is also used. One would be
hard-pressed to come up with a different character to represent the
same concept in Han, aside from the traditional Chinese counterpart
"؈" (U+8C93).

I don't know what the present thinking is on the idea of non-semantic
TLDs, but IMHO the social expectations of DNS usage is cast in stone.
Jon's idea would simply shift the semantics to the second level,
thereby creating 24 roots instead of a single "."


On Fri, Jul 4, 2008 at 1:50 PM, John C Klensin <john-ietf at> wrote:
> Vint,
> In the ASCII space, there have been three explanations offered
> historically for the one-character prohibition on top and
> second-level domains.   I've written variations on this note
> several times, so will just try to summarize here.  Of the
> three, the first of these is at best of only historical interest
> and may be apocryphal and the second is almost certainly no
> longer relevant.  The third remains significant.
> (1) Jon has been quoted as suggesting that we could have
> eliminated many of the problems we now face with TLDs and
> simultaneously made the "no real semantics in TLD names" rule
> much more clear had we initially allocated "b".."y" as TLDs.
> Then, when someone asked for an assignment, it would have been
> allocated at random to one of those domains.  While this has a
> certain amount of appeal, at least in retrospect, there is
> probably no way to get from where we are today to that model...
> unless actions taken in the near future so ruin the current DNS
> tree as a locus for stable and predictable references that we
> need to start over with a new tree.  I don't think that a "have
> to start over" scenario is at all likely, but I no long believe
> it to be impossible.
> (2) There was an idea floating around for a while that, if some
> of the popular TLDs "filled up", one could create single-letter
> subdomains and push subsequent registrations down the tree a
> bit.  For example, if .COM were declared "full", then "",
> "", etc., would be allocated and additional reservations
> pushed into subdomains of those intermediate domains rather than
> being registered at the second level.  Until and unless the
> conventional wisdom that adding more names to .COM merely
> requires more hardware  and/or bandwidth, that won't be a
> "filled up" point at which this sort of strategy could be
> triggered.  Worse, trying to use single-letter subdomains as an
> expansion mechanism would raise political issues about putting
> latecomers at an advantage that would be, IMO, sufficient to
> completely kill the idea.  In the current climate, I think the
> community would decide that it preferred a disfunctional DNS if
> that were ever the choice (see the "start over" remark above).
> (3) At least in the discussions that led up to RFC 1591, and
> probably much earlier, there were concerns about reducing the
> likelihood of false hits if the end user made single-character
> typing errors.  With only 26 (or maybe 36) possible characters,
> it could just about be guaranteed that all of them would be
> registered and that _any_ typing error would yield a false
> match.  That, in itself, has been considered sufficient to
> prohibit single-letter labels and, by extension, to be fairly
> careful about two-letter ones.   There have been arguments on
> and off over the years as to whether this is a "technical"
> reason or an attempt to set policy.  Even though the mismatches
> would obviously not cause the network to explode or IP to stop
> working, at least some of us consider the informational
> retrieval and information theoretic reasons to insist on more
> information in domain name labels in order to lower the risk of
> false positive matches to be fully as "technical" as something
> that would have obvious lower-level network consequences.
> Others --frankly especially those who see commercial advantage
> in getting single-letter names-- have argued that this position
> is just a policy decision in disguise.
> Note that, with slight modifications, the second and third
> arguments apply equally well to TLD allocations and to SLD
> allocations, especially in popular domains.
> The reasoning associated with the third case also applies to any
> other script that contains a fairly small number of characters.
> One could manage a long philosophical discussion as to whether
> there are sufficient characters in the fully-decorated
> Latin-derived collection to eliminate the problem, but an
> analysis of keyboard and typing techniques/ input methods for
> that range of characters would, IMO, yield the same answer --
> single-letter domains are just not a good idea and two-letter
> ones near the top of the tree should be used only with great
> caution.
> On the other hand, the same reasoning would break down when
> confronted with a script that contains thousands of characters,
> such as the "ideographic" ones.  There are enough characters
> available in those scripts that one can presumably not worry
> about single-character typing errors (and one can perhaps worry
> even less if the usual input methods involve typing
> phonetically, using a different script, and then selecting the
> relevant characters from a menu -- in those cases, the phonetic
> representations are typically more than a character or two long
> and the menu selection provides an extra check about false
> matches).
>     john
> --On Thursday, 03 July, 2008 19:04 -0400 Vint Cerf
> <vint at> wrote:
>> seems odd to me too, James.
>> vint
>> On Jul 3, 2008, at 6:14 PM, James Seng wrote:
>>>> At the moment, the condition is "no single Unicode code
>>>> point." To the extent that a single CJK ideograph can be
>>>> expressed using a single Unicode code point, this would
>>>> represent the situation to which you say you would object. I
>>>> will dig through my notes to find out why the "single
>>>> character" condition was adopted -
>>> Would you be able to explain why the condition is "no single
>>> Unicode code point"? Whats the technical basis for that?
> _______________________________________________
> Idna-update mailing list
> Idna-update at


More information about the Idna-update mailing list