L2/03-112

Source:  "Roozbeh Pournader" <roozbeh@sharif.edu>
Date:    Wednesday, March 05, 2003 19:12
Subject: New Arabic controls and Arabic joining

The new Arabic controls, U+0600..U+0603, and U+06DD (END OF AYAH) are "Cf"
characters, while ArabicShaping.txt specifies in its preamble that "Cf"s
are transparent with regard to Arabic joining, while these are rather
non-joining as they break the connection between the letter before them
and the letter after them (that may actually appear above them in
display).

1. Suggested quick change: Change the formula in ArabicShaping.txt from:

#   T = Mn + Cf - ZWNJ - ZWJ

to something like

#   T = Mn + Cf - Special

where "special" are control characters that their joining type
is specifically mentioned in the ArabicShaping.txt file. Add ZWNJ,
U+0600..U+0603, and U+06DD to the file with a Joining type of "U".

2. Suggested long term change: Establish a new joining class for
non-joining controls. Possibly add others like INVISIBLE TIMES and
INVISIBLE SEPARATOR to this class.

	Roozbeh