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RE: RTL directionality in LaTeX

From: Murray Sargent <murrays@exchange.microsoft.com>
Date: Tue, 5 Nov 2013 19:55:46 +0000
To: Peter Krautzberger <peter.krautzberger@mathjax.org>, Frédéric WANG <fred.wang@free.fr>
CC: Khaled Hosny <khaledhosny@eglug.org>, "www-math@w3.org" <www-math@w3.org>, Azzeddine LAZREK <a_lazrek@yahoo.fr>
Message-ID: <ee27d4704eb646b1913f109e92ea4f3a@DFM-TK5MBX15-06.exchange.corp.microsoft.com>
See also the Unicode Arabic Mathematical Alphabetic Symbols<http://www.unicode.org/charts/PDF/U1EE00.pdf>, which were standardized after the Arabic math reference below was published. A Unicode-enabled LaTeX could represent these symbols directly as Unicode characters. Alternatively, they can be represented as styles. The Unicode representation has the advantage that it can be transmitted using plain text.


From: Peter Krautzberger [mailto:peter.krautzberger@mathjax.org]
Sent: Tuesday, November 5, 2013 11:29 AM
To: Frédéric WANG
Cc: Khaled Hosny; www-math@w3.org; Azzeddine LAZREK
Subject: Re: RTL directionality in LaTeX

I'm wondering how many BIDI variants there are to consider. From http://www.w3.org/TR/arabic-math/, I see 3-4 different styles of BIDI math. These should be reflected in a TeX-like syntax, I think.

Are there other variants?

On Tue, Nov 5, 2013 at 6:57 AM, Frédéric WANG <fred.wang@free.fr<mailto:fred.wang@free.fr>> wrote:
Le 05/11/2013 15:43, Khaled Hosny a écrit :

Since the direction of text and math are not always the same (many RTL languages set math LTR), the command need to be explicitly for math.
Yes, that was one of the reason to make Gecko interpret CSS direction property the same way as MathML dir attribute (the other reason is that it simplifies the implementation). In an ideal world where MathML implementations are compatible with CSS, people could then just use something like

math { direction: rtl; }

or with CSS selectors

div.MyArabicDiv math { direction: rtl; }

to set the direction on all the math elements rather than having to explicitly attach a dir="rtl" attribute on each one.

But if it is just some pseudo-LaTeX syntax, I don't think the actual notation matters much, but \rtl{} looks more LaTeX-like to me.
Or perhaps \dir[rtl]{...} with an optional parameter so that someone can still switch back to LTR with \dir[ltr]{...}.

Frédéric Wang
Received on Tuesday, 5 November 2013 19:56:47 UTC

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