title_body: Developing a new file format for E-readers that supports special languages
upvoted_answer: The epub3 standard offers a couple of new attributes specifically for RTL languages such as Persian and most free ePub3 apps, for example, ADE 4, Azardi, Gitden Reader and iBooks display epub3 RTL books fine.
  
  (There's an Arabic test book at the official epub3 samples website that you can use for testing.)
  
  BTW, if you happen to have a Kindle, you'll need to convert epubs to AZW3 files with Calibre, because the old MOBI format doesn't support RTL languages.