Re: Difference between Bidi_Class 'R' and 'AL'

From: Richard Wordingham <>
Date: Wed, 24 Aug 2011 20:35:12 +0100

On Wed, 24 Aug 2011 08:35:48 -0700
"Doug Ewell" <> wrote:

> UAX #44, Table 13 ("Bidi_Class Values") includes the following
> descriptions:
> R - Right_To_Left - any strong right-to-left (non-Arabic-type)
> character AL - Arabic_Letter - any strong right-to-left (Arabic-type)
> character
> But I can't find any definition, here or elsewhere, of what
> constitutes an "Arabic-type" or a "non-Arabic-type" letter.

Expanding on Mark's answer, the basic difference is whether a character
of Bidi class ET (percentage-type and currency symbols) when stored
before or after European or Persian etc. digits goes to their left or
right. For Arabic, these symbols are not part of the number; for
Hebrew, they are part of the number. I'm not I understand the effect on
ES (variants of plus and minus signs) - may be it says that 'e-less'
exponents in Fortran output go on the left in Arabic but on the right
in Hebrew and LTR scripts.

Received on Wed Aug 24 2011 - 14:39:46 CDT

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