Private Use areas

Mark E. Shoulson via Unicode unicode at
Tue Aug 21 18:45:10 CDT 2018

On 08/21/2018 02:03 PM, Ken Whistler via Unicode wrote:
> On 8/21/2018 7:56 AM, Adam Borowski via Unicode wrote:
>> On Mon, Aug 20, 2018 at 05:17:21PM -0700, Ken Whistler via Unicode wrote:
>>> On 8/20/2018 5:04 PM, Mark E. Shoulson via Unicode wrote:
>>>> Is there a block of RTL PUA also?
>>> No.
>> Perhaps there should be?
> This is a periodic suggestion that never goes anywhere--for good 
> reason. (You can search the email archives and see that it keeps 
> coming up.)
> Presuming that this question was asked in good faith...

Yeah, I know there has been talk about such things, and I also knew that 
whether or not there was an RTL block (which I did not remember for 
certain), there weren't going to be any *changes* in the PUA, and we 
were going to have to make do with what there was.  There's no way to 
anticipate all the possible properties people would want in the PUA, 
though I remember thinking it was probably wrong to make the PUA 
*strongly* LTR; I know there's a not-strongly flavor too.

Best we can do is shout loudly at OpenType tables and hope to cram in 
behavior (or at least appearance, which is more likely all we can get) 
that vaguely resembles what we're after.  And that's not SO awful, given 
what we're dealing with.

> As I see it, the only feasible way for people to get specialized 
> behavior for PUA ranges involves first ceasing to assume that somehow 
> they can jawbone the UTC into *standardizing* some ranges for some 
> particular use or another. That simply isn't going to happen. People 
> who assume this is somehow easy, and that the UTC are a bunch of 
> boneheads who stand in the way of obvious solutions, do not -- I 
> contend -- understand the complicated interplay of character 
> properties, stability guarantees, and implementation behavior baked 
> into system support libraries for the Unicode Standard.

The whole point of the PUA is that it *isn't* standardized (by the 
UTC).  It might have been nice to make some more varied choices of 
things that couldn't be left unspecified, but you're still going to wind 
up with "but there aren't any PUA codepoints that are JUST what I 
need!"  And, as said, it's too late now.


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