Re: RTL PUA?

On 08/19/2011 08:03 PM, Michael Everson wrote:
> On 19 Aug 2011, at 15:13, Doug Ewell wrote:
>
>> The PUA is supposed to be a free and open sandbox, without reserved
>> or allocated zones.
>
> Nevertheless, inherent directionality is something that computers
> take notice of. There would be no harm in having a RTL PUA area.

To set restrictions on the usage of the PUA by specifying specific LTR
and RTL ranges would be to undermine the definition of the PUA, IMHO.

As Doug correctly pointed out, anybody can do anything with PUA
codepoints -- render them LTR, RTL or even top-to-bottom or
bottom-to-top or boustrophedon if they can.

How would it be appropriate to assign directionality to PUA characters?
I personally feel even their BC=L is wrong.

>> My question would be why the PUA is designated as 'L' by default at
>> all, instead of, say, 'ON'.

As I already said, it would seem then that the correct (or at least,
*best*) BC for the PUA is ON, at least implying that the Unicode
Standard itself doesn't specify any directionality for these characters,
whether that is the original intention of BC=ON or not (because it might
be to actually assert that they *are* *neutral* [which means exactly
what I'm not sure as they *have* to be written in *some* direction...]).

>> So your private agreement, in addition to specifying the meaning of
>> your PUA characters and probably some sample glyphs, can also
>> specify their properties, overriding the default properties.
>
> Gods know I wouldn't have any idea how to get my operating system to
> honour such a declaration.

See my other mail for differences in abilites. You can do a font, others
can't. Others can do rendering engines, you can't. C'est la vie!

>> There's a lot of misinformation and FUD about the PUA, and
>> unfortunately I expect at least one response of the form "The PUA
>> is evil, don't use it," which accomplishes very little.
>
> I just think we need some PUA that's RTL.

Please don't take this amiss, but I would like to hear more than just a
restatement of your opinion (which is clear enough), more especially in
the nature of sufficient arguments as to how that would be meaningful or
helpful to allocate RTL PUA, or as to how it would *not* undermine the
very *definition* of the PUA! :)

-- 
Shriramana Sharma