In Iran there are a few characters that are super common but not in codepage 1256. It's characters that belong to ARABIC LETTER FARSI YEH

Below is an example

نیایش

character: U+06CC

But I don't really know if there is a better solution for Iran outside of unicode than 1256... 

Found this character also discussed here:

I think there is also an extended version of 1256 - could mkgmap change to 1256 extended? I think this is what is mentioned on here: https://en.wikipedia.org/wiki/Windows-1256

I guess 06CC is part of the extended 1256 and some other arabic countries are affected too.

Not sure if there is something that can be done or not. But right now for Iran non unicode maps read quite badly - especially due to 06CC.