Subject: [precis] Nicknames starting with a digit and the Directionality Rule

From: "Peter Occil" <[email-masked]>
Date: Fri, 21 Nov 2014 23:34:18 -0500

The nickname document incorporates the Bidi Rule as its directionality rule when enforcing nickname strings.

However, the Bidi Rule disallows names such as "1example" or "13371337", which begin with a digit,  and it is plausible for nicknames like those to occur. (The first condition of the Bidi Rule allows names to begin only with L, R,  or AL characters, and an ASCII digit is an EN.) This issue is mentioned nowhere in the framework or nickname documents and ought to be addressed somehow.

--Peter

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From: Peter Saint-Andre - &yet <[email-masked]>
Date: Sun, 23 Nov 2014 13:00:00 -0700

On 11/21/14, 9:34 PM, Peter Occil wrote:
> However, the Bidi Rule disallows names such as "1example" or "13371337",
> which begin with a digit,  and it is plausible for nicknames like those
> to occur. (The first condition of the Bidi Rule allows names to begin
> only with L, R,  or AL characters, and an ASCII digit is an EN.) This
> issue is mentioned nowhere in the framework or nickname documents and
> ought to be addressed somehow.

Hmm, that is indeed an unfortunate consequence of using the Bidi Rule. 
However, RFC 5893 says:

    The purpose of this document is to establish a rule that can be
    applied to Internationalized Domain Name (IDN) labels in Unicode form
    (U-labels) containing characters from scripts that are written from
    right to left.  It is part of the revised IDNA protocol [RFC5891].

    When labels satisfy the rule, and when certain other conditions are
    satisfied, there is only a minimal chance of these labels being
    displayed in a confusing way by the Unicode bidirectional display
    algorithm.

    The other normative documents in the IDNA2008 document set establish
    criteria for valid labels, including listing the permitted
    characters.  This document establishes additional validity criteria
    for labels in scripts normally written from right to left.

    This specification is not intended to place any requirements on
    domain names that do not contain characters from such scripts.

So does it really apply if no RTL characters are present?

If we try to define some other rule for handing of bidirectionality, we 
will almost certaily get it wrong...

Peter

-- 
Peter Saint-Andre
https://andyet.com/