[apps-discuss] CONTEXTJ in TLD DNS-Labels (draft-liman-tld-names-05)

Behnam Esfahbod <behnam@esfahbod.info> Thu, 30 June 2011 20:56 UTC

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Date: Thu, 30 Jun 2011 16:56:02 -0400
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Subject: [apps-discuss] CONTEXTJ in TLD DNS-Labels (draft-liman-tld-names-05)
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The restriction rules of the latest draft for "Top Level Domain Name
Specification", section 4 [1], is unfortunately very restrictive for
some languages, including Persian language (in Arabic script).

  2.  the derived property value of all code points, as defined by
      [RFC5890], is PVALID;

  3.  the general category of all code points, is one of { Ll, Lo, Lm,
      Mn }.

These restrictions are simply ignoring the characters with CONTEXTJ
derived property value, which was added to IDNA2008 protocol to
support Persian (and some Indic languages) in domain name labels [2].
Restricting TLD DNS-labels to only PVALID characters makes it
impossible to write very basic
words of Persian language. For example, "خانه‌ها" (English: houses)
and "کوه‌ها" (mountains) which are basic Persian words include U+200C
(ZERO WIDTH NON-JOINER or ZWNJ) and it is impossible to write those
words in Unicode without using ZWNJ.

IDNA2003 didn't support ZWNJ in lables and that practically made the
standard broken for Persian language. Now that this problem has been
resolved, we expect that TLD DNS-Labels also benefit from the effort
that has been put into the new standard and allow the CONTEXTJ
characters, specially U+200C (ZWNJ), in TLD DNS-Labels.

Hereby, I would like to request reconsidering the restriction rules of
TLD DNS-Labels and to allow characters with CONTEXTJ derived property
value in the labels. (Of course the IDNA2008 contextual restrictions
for CONTEXTJ characters must apply.)

Thanks in advance,
-Behnam Esfahbod
ISOC and ICANN TLD Variant Issue Project, Arabic-Script Case Study Team member

1: https://tools.ietf.org/html/draft-liman-tld-names-05#section-4
2: https://tools.ietf.org/html/rfc5894#section-3.1.2