Comments on IDNA Bidi

Michel Suignard michelsu at
Wed Jan 16 19:07:02 CET 2008

Please don't confuse the bidi terminology more than it needs to be. There is no difference between display and visual order, except that I would agree with Cary that display order is probably a better term and in fact Unicode uses the 'display' term more often than 'visual'. However the visual order (or visual representation) term has been used in documents related to bidirectionality for a long time. I came across that term since the late 80s when general purpose Operating Systems I was dealing with started to implement bidirectional handling and it was used frequently by the bidi experts at that time (mostly from IBM) and the logical versus visual order comparison has taken root since then. So in practice 'visual' and 'display' order tends to be used interchangeably.

In addition, what is referred in the message below as 'display order' is unclear to me. What is registered is for sure what everybody else would call 'logical order'. Unicode is not a standard to just manage what you called 'display order'. See page 19 of the Unicode standard 5.0 for further details concerning logical order and the interaction with readable (displayed) text. Keyboard order is another beast altogether as it depends on the input method editor you use and varies a lot among implementation of writing systems input.

And please stop to try to put a wedge between ISO 10646 and Unicode. ISO 10646 for the longest time has had normative references to the Unicode bidi algorithm and the normalizations forms and both standards are more and more aligned not only in content and terminology (I guess I should know being project editor for 10646).

For the foreseeable future there is no alternative to the Unicode/10646 tandem, we can improve and there is room for that, but trying to create a new paradigm does not seem a useful exercise to me.

Sorry for this slightly out of topic set of remarks.


-----Original Message-----
From: idna-update-bounces at [mailto:idna-update-bounces at] On Behalf Of JFCM
Sent: Wednesday, January 16, 2008 7:20 AM
To: Cary Karp
Cc: idna-update at
Subject: Re: Comments on IDNA Bidi

At 11:40 16/01/2008, Cary Karp wrote:
>"Display" strikes me as the more objective term (being an attribute of
>what the machine does), to which "visual" is a cognitive correlate
>(being in the mind of the beholder).

I agree. When you enter a name on a keyboard, this is the display
order. When you read it on an ad, this is the visual order. Unicode
is a standard to manage the display order (printing). IDNA wants to
use it in a visual order (the order used to register it). This
creates several impossibilities to address the DNS, zone
administrators, security, etc. needs, including because the same
visual may correspond to several display codes or even sequences and
therefore orders.

The only DNS needs are a unique registration order and a unique
registration correspondance between display and visual. Bidi is a no
problem once the direction is set (it results from the display order
qualias [position and left to right or right to left]).

This leaves us with two plans:
- plan IDNA, to best use the current Unicode oriented proposition on
a temporary basis, that countries and semantic addressing can use now.
- plan IDNB, to devise a universal visual sign secured set
interoperable with ISO 10646 and a conversion from that UV3S to ASCII
that can be consistently used in every semiotic applications, and at
International Network presentation layer (that we also have to devise
and implement).

Why to support the idea of a single authoritative root, so the same
ASCII DN resolves the same IP everywhere, if the same U-label does
not resolve first to the A-label for ever?

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