UAX #9: applicability of higher-level protocols to bidi plaintext

[Eli Zaretskii via Unicode]

> Date: Tue, 10 Jul 2018 13:37:56 +0200
> Cc: unicode Unicode Discussion <unicode at unicode.org>
> From: Philippe Verdy via Unicode <unicode at unicode.org>
> 
> Your "standard compliant" plain text editor just forces a LTR default for the whole document, and does not
> tolerate that individual paragraphs may start with an undetermined direction (which should then be determined
> by the first character on the line that defines a direction.)
> In my opinion, even if your text editor still does not enforce the default left margin side for aligning the text, it
> should still treat individual paragraphs isolately and determine the direction to use (each paragraph break
> should cancel the direction inheritance).
> 
> A plain text editor should not have a default strong LTR default, it should have a weak undetermined direction,
> independantly of the fact that it will align the pagraph to the left of right margin according to the resolved
> direction of the first character.

I think you may be missing the point.  The issue raised by Shai is not
what should be the default, the issue is whether each program can have
its own rules for overriding the default paragraph direction by
applying "higher-level" protocols private to the program, and not
shared by other programs when they present the exact same text.

There's no argument about the default -- it should indeed behave as
described in the UBA, i.e. look for the first string directional
character in each isolate run.