U+303B VERTICAL IDEOGRAPHIC ITERATION MARK

[Kenneth Whistler]

I agree with Wil Tan about this.

The Vertical Kana repeat marks (3031..3035) make no sense
in IDN's, particularly since they will certainly be forced
into horizontal display contexts, where they could accomplish
nothing but introduce mischief and confusion.

As for U+303B VERTICAL IDEOGRAPHIC ITERATION MARK, it is
also useless in IDN's, and I don't think it is helpful or
pertinent to clutter up the CONTEXTO rules in the appendix A
listing trying to come up with an appropriate rule for this.

As for attempting to stand on principle that IDNA should not
categorize characters as DISALLOWED unless shown to be
harmful, we already crossed that bridge a long time ago
by ruling 1000's of symbols as DISALLOWED on general
principle, even though they are less problematical than
these vertical display characters.

And finally, there is no good reason whatsoever why U+303B
should be CONTEXTO (and have that stand as some kind of
precedent that we can't reverse to make it DISALLOWED
in the table), when all these other, more problematical
vertical form characters are sitting in the table as PVALID
and not CONTEXTO. So from the point of view of
consistency and minimal confusion for implementers,
the best choice is to make the lot DISALLOWED and be done
with it -- *particularly* if we agree that:

"Sane registry policy everywhere will still probably set this to
registry-disallowed."

--Ken

> I think the following should be DISALLOWED:
> 
> U+3031: Lm: VERTICAL KANA REPEAT MARK
> U+3032: Lm: VERTICAL KANA REPEAT WITH VOICED SOUND MARK
> U+3033: Lm: VERTICAL KANA REPEAT MARK UPPER HALF
> U+3034: Lm: VERTICAL KANA REPEAT WITH VOICED SOUND MARK UPPER HALF
> U+3035: Lm: VERTICAL KANA REPEAT MARK LOWER HALF
> U+303B: Lm: VERTICAL IDEOGRAPHIC ITERATION MARK
> 
> Mainly because U+3033 looks like protocol character (forward slash)
> and thus harmful IMO. Since this is a group of characters with related
> usage, and that Yoneya-san, Martin Dürst and John suggested that they
> should be disallowed:
>   http://www.alvestrand.no/pipermail/idna-update/2009-April/004398.html
> 
> =wil