From: Michael Everson <>
Date: Fri, 19 Aug 2011 15:48:52 +0100

On 19 Aug 2011, at 15:34, Shriramana Sharma wrote:

> On 08/19/2011 07:43 PM, Doug Ewell wrote:
>> My question would be why the PUA is designated as 'L' by default at all,
>> instead of, say, 'ON'.
>> ...
>> do present the impression that these code points are somehow reserved
>> for strong-LTR characters, and also for non-reordrant characters (i.e.
>> no combining marks), neither of which is true.
> I entirely agree! There then should be an effort to officially change the BC of these characters to ON, would you say? I mean, what kind of implementations could such a change affect adversely?

There is plenty of space. There would be no difficulty in assigning some rows to a RTL PUA. Mucking about with the directionality of the existing PUA would be extremely unwise.

> Conceivably certain closed user-groups could be using closed-distribution rendering engines which would support bidi and glyph reordering or such for PUA codepoints.

Not everyone is a programmer and can devise a rendering engine. But lots of people can make fonts that could support a RTL conscript or some private Arabic characters.

> In which case, the only change that needs to be done to affirm that the PUA can be used for both LTR and RTL scripts is to change the BC of all those characters to ON.

I wouldn't support that.

Michael Everson *
Received on Fri Aug 19 2011 - 09:50:15 CDT

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