consensus Call: TATWEEL

Ebw ebw at
Tue Mar 24 00:47:02 CET 2009

Hyphen and tatweel are very unlike.

Sent from my iPhone, painfully.

On Mar 23, 2009, at 2:06 PM, John C Klensin <klensin at> wrote:

> --On Tuesday, March 24, 2009 01:06 +0430 Alireza Saleh
> <saleh at> wrote:
>> I think this is the registry  choice to make it DISALLOW.
>> Would you  please tell me the reason of using  low-rise or
>> Hyphen in English and  why it is allowed both for DNS and IDN ?
> That decision was, for all practical purposes, made around 1971.
> The intention was to have a way to divide mnemonics and
> structure names well before the DNS came along.  So, for
> example, we had "MIT-Multics" (note the hyphen) which evolved
> into "Multics.MIT.EDU".  The hyphen was then included in the
> DNS, at least in large part, in order to support the transition
> strategy which migrated from "MIT-Multics" (standalone host name
> and in the host table) to MIT-Multics.ARPA" (transitional DNS
> name) to "Multics.MIT.EDU" (target DNS name).   I have no idea
> how many people thought of it as transitional in the DNS
> (gradually disappearing as we shifted from host-table names to
> DNS ones) or a permanent features.
> Low-line (underscore) has never been permitted, partially
> because of visual confusion issues with hyphen (there is at
> least one other reason, but it can be easily explained only in
> terms of 1403 print trains :-(  ).
> And hyphen is a full character in Latin script, going back
> centuries, and not used for justification, calligraphy, or
> typography only.  For some applications of the latter, there are
> other characters to represent the EMdash and ENdash... and they
> are not permitted in IDNs either.
> If there are lessons in the hyphen, they are that one should be
> quite careful to avoid, or at least consider the implications
> of, transition strategies that are likely to last forever.
>      john
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