Bidi paragraph direction in terminal emulators (was: Proposal for BiDi in terminal emulators)

Eli Zaretskii via Unicode unicode at
Mon Feb 4 10:53:22 CST 2019

> Date: Mon, 4 Feb 2019 01:19:21 +0000
> From: Richard Wordingham via Unicode <unicode at>
> On Sun, 03 Feb 2019 19:50:50 +0200
> Eli Zaretskii via Unicode <unicode at> wrote:
> > Do you see how this is carefully formatted to avoid overflowing an
> > 80-column line of a typical terminal?  Now suppose this is translated
> > into a RTL language, which causes the Copyright line to start with a
> > strong R letter (because "Copyright" is translated).  You will see the
> > first line flushed to the right margin, then the next line flushed to
> > the left margin (because it's a separate paragraph, and starts with a
> > strong L letter).  Then the line which says "The default action..."
> > will again start at the right.  And so on and so forth -- the result
> > is extremely ugly.
> Depending on the environment.  If you look at it in Notepad, all lines
> will be LTR or all lines will be RTL.

That's because Notepad implements _only_ the higher-level protocol for
base paragraph direction: there's no way to make Notepad determine the
direction by looking at the text.

> Would not a careful translator either ensure that each non-blank
> line had a strong character and that all first strong characters
> were (a) L, (b) R or (c) AL?

This is very hard in practice, and is a tremendous annoyance when
translating message catalogs to RTL languages.  Translation is a hard
enough job even without this complication.

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