From: Mark E. Shoulson <>
Date: Fri, 19 Aug 2011 11:04:58 -0400

On 08/19/2011 10:57 AM, Doug Ewell wrote:
> "Mark E. Shoulson"<mark at kli dot org> wrote:
>>> 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.
>> I don't know if you can even do this. My understanding of the
>> rendering process is very sketchy, but I seem to recall that things
>> like directionality cannot be specified by a font or other easily
>> transmissible piece of information, but has to be baked into the
>> application or rendering engine itself. This severely limits the
>> utility of the PUA, if applications that use it have to be written
>> from scratch each time. At least with stuff that is font-dependent,
>> you can use ordinary word-processors that honor OpenType or Graphite
>> or whatever.
> I didn't say that applications or rendering engines are able to accept
> your overridden properties and apply them, right out of the box, at
> least not today.
But they work Just Great for LTR scripts in the PUA, but not for RTL
scripts. Isn't that kind of bias counter to the whole point of the PUA
and Unicode in general? And it isn't only due to implementors, either:
Unicode specifies LTR directionality for the PUA (which is where we came
into this discussion in the first place.) Aren't we supposed to do
something about that?

Received on Fri Aug 19 2011 - 10:05:48 CDT

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