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).
Typotheque designs and develops Unicode-compliant fonts. Below are some instructions for using Unicode fonts to set Devanagari texts.
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.