Some old text documents working with Arabic or Indic languages use 8-bit encoding, which required to use proprietary fonts. Such fonts can only use 256 glyphs, which is not sufficient for correct rendering of Devanagari (or other 10 Indic writing scripts).
In order to use Arabic fonts, you need to use special versions of InDesign, PhotoShop or Illustrator. These versions are labeled ME (Middle Eastern) and support bi-directional text setting for Arabic, Farsi and Hebrew. The regular version of Adobe CS3 doesnʼt support Arabic text setting.
TPTQ Arabic offers Multilingual Unicode Compliant Fonts in WGL4, and larger character sset supporting over 80 languages in standard Latin, Central European, Baltic, Turkish, Greek, Cyrillic, and Arabic encodings.