Re: Multiple private agreements (was: RE: Code pages and Unicode)

From: Doug Ewell <>
Date: Wed, 24 Aug 2011 07:19:57 -0700

Philippe Verdy <verdy underscore p at wanadoo dot fr> wrote:

>> (1) a plain-text file
>> (2) using only plain-text conventions (i.e. not adding rich text)
>> (3) which contains the same PUA code point with two meanings
>> (4) using different fonts or other mechanisms
>> (5) in a platform-independent, deterministic way
>> One or more of the numbered items above must be sacrificed.
> The only numbered item to sacifice is number (3) here. that's the case
> where separate PUA agreements are still coordinated so that they don't
> use the same PUA assignments. This is the case of PUA greements in the
> Conscript registry.

Number 3 was the entire basis for srivas's question:

"If same codes within PUA becomes standard for different purposes, how
to get both working using same font?
How to instruct text docs, what font if different fonts are used?"

Changing the question around, so that we are no longer talking about one
code point with two meanings, doesn't accomplish anything.

> With only this exception, you can perfectly have separate agreements
> (using multiple fonts transporting them), for rendering a plain-text
> document. Of course the PUA only agreement stored in the font are the
> set of glyphs, and the display properties. Other properties (for
> collation, case mappings, text segmentation, and so on...) are not
> suitable for being in the font, but they are not needed for correct
> editing (without automated case changes) or for correct rendering.

We have different views concerning the relative importance of these
"other" properties, and I'm not going to try further to convince you.

Doug Ewell | Thornton, Colorado, USA | RFC 5645, 4645, UTN #14 | | @DougEwell ­
Received on Wed Aug 24 2011 - 09:25:12 CDT

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