Katakana Middle Dot again (Was: tables-06b.txt: A.5, A.6, A.9)

[John C Klensin]

(Combining two messages for simplicity and compactness)

--On Friday, August 07, 2009 23:28 +0900 Yoshiro YONEYA
<yone at jprs.co.jp> wrote:

>> Third, I have not been able to understand the utility of
>> allowing a   label consisting only of IDEOGRAPHIC CLOSING
>> MARK and KATAKANA MIDDLE   DOT.
> 
> I can't negate demand for such sequences.

>...

> A sequence of IDEOGRAPHIC CLOSING MARK, KATAKANA MIDDLE DOT
> and  IDEOGRAPHIC CLOSING MARK is a possible example.  I think
> its  probability will be very low, but I think the desire is
> reasonable.

We can imagine "demand" or "desire" for almost any sequence.  As
one example among many, I would imagine that the ASCII string
"@#$%&" would be quite in demand if permitted it, and several
similar strings, actually have semantics in some contexts
although I'd be hard-pressed to explain how they would be
pronounced.

If this is really a symbol, punctuation, or spacing mark --as
the name implies-- then our general principles would argue for
banning it entirely.  Unless someone makes the case for its
having been misclassified, I don't see a reason to make an
exception to Unicode's classification of it as "Lo", so it would
remain a PVALID character.   But, just as was the case for
Middle Dot, I think we need to hear a compelling argument for
why it is actually necessary to have labels that consist only of
one or more closing marks and middle dots.

At least for me, it would help to know how a label consisting of
   Ü+3006 U+30FB
would be pronounced and what it would mean.  

It would also help me to understand how a normal (not computer
expert) reader of Japanese would read 
  U+30A2 U+30AA U+30FB U+30A2 
as different from
  U+30A2 U+30AA U+30FB U+30A2 U+3006
in a label.

Otherwise, I think that the observation that Harald and I have
made in different ways should probably apply: It is in
everyone's interest to minimize the number of exceptions to
those that are really needed to support the writing system.  In
this example, I believe that case has been made for permitting
Katakana Middle Dot despite the fact that it is classified as
punctuation.  But the idea of making a second exception just to
support an exception makes me very nervous, especially if the
argument for it is that someone might desire such a label.

I want to stress that I haven't made my mind up about this.  I'm
just trying to understand the requirement --and whether or not
there is an important requirement-- better.

best regards,
    john