Tables and contextual rule for Katakana middle dot

Yoshiro YONEYA yone at
Mon Apr 6 09:36:16 CEST 2009

Dear John-san and Patrik-san,

In reality, in Japanese context, KATAKANA MIDDLEDOT (U+30FB) is used 
to compose names and to concatenate words, so it is used various places.
And sometimes preceeding and/or succeeding character is alphabet or digit 
([a-zA-Z0-9]).  Furthermore, KATAKANA MIDDLEDOT is sometimes placed at 
the beginning or the ending of names.

Therefore, it is very difficult to define rule set for KATAKANA MIDDLEDOT.
What I can say is:

    (KATAKANA MIDDLEDOT) MUST be used in Japanese context.


Yoshiro YONEYA <yone at>

On Fri, 03 Apr 2009 23:31:23 -0400 John C Klensin <klensin at> wrote:

> Patrik,
> Just so this doesn't accidentally fall through the cracks...
> It is clear from the discussion last week that I simply got the
> contextual rule for Katakana Middle Dot (U+30FB) wrong in what
> is rule/Appendix A.12 in Tables-05.  I had understood that I had
> been told it was used only with Katakana; the JET I-D and
> Monday's presentation make it clear to me (and I assume others)
> that it can be used between any pair of Japanese characters.
> The overview now reads:
>    Adjacent characters MUST be Katakana.
> It should be:
>    Adjacent characters MUST be Hiragana, Katakana, or Han.
> The associated Rule Set will, of course, have to be updated to
> match.
> Yoneya-san,
> Could you please check the above and verify that I have stated
> the rule correctly and not simply replaced one error with
> another?  Also, the Unicode table Scripts.txt lists several
> Hiragana and Katakana characters are members of the "Common"
> group rather than being script-specific.  Could you verify that
> none of those are relevant (e.g., that they are DISALLOWED or
> otherwise prohibited from appearing in domain name labels)?
> thanks,
>     john
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