Custom Transliteration Characters
Transliteration is the conversion of a text from one script to another. In order to do this precisely certain letters that have different sounds in the source language have to be represented by special characters, often with diacritical marks added.

For the transliteration of the Arabic language there are a few different transliteration systems to convey the letters and pronunciations unique to the Arabic language. In my experience the most popular and easiest to use is the Library of Congress system. The characters in this system used to convey the arabic letters are as follows:
Frustrated with the lack of decent kerning in fonts with the necessary characters for the transliteration of the Arabic language i took it upon myself to create my own characters using the excellent Indesign Script by Indiscripts IndyFont.

My first choice for typesetting longform texts is always Robert Slimbach's Garamond Premier Pro. I have not found another font that has such an economic and elegant ability to fit words on the page perfectly. Unfortunately the characters required to transliterate the Arabic language into the latin script are missing in this font. I needed the Dd, Hh, Ss, Tt & Zz to have dots underneath them.
Starting with the letters needed without the dots in the original font and the closest looking characters that do have dots underneath them i started to explore how to add the diacritical dots underneath the letters in keeping with the original font. I also decided to use Adobe's Text Pro font as a reference point. Text Pro does have all the required transliteration characters i needed, but it is not as elegant a font as Garamond Premier Pro in my opinion. 
Using the characters that have a dot underneath in the original font and also the isolated diacritical dots i tried to come to an good understanding of what might be the appropriate size and shape of the required dots, and most importantly where they should be positioned underneath the letter. I also took into consideration the different font weights as well.
After deciding on the most suitable dot i started the creation of the transliteration characters using Indy Font. Indy Font is a script used within Indesign to create your own customized font sets. As i understand it, it was created for such tasks that i had undertaken. For an overview on how i created the characters check out Indiscripts 'IndyFont' here: http://www.indiscripts.com/category/projects/IndyFont This short basic video gives you an idea of how easy using IndyFont can be:
But i used a slightly different approach to the video. Initially i used the same letter and unicode from the original font as the template, so that i would get the look and placement of the dots as visually correct as i could, i then changed the unicode character code within IndyFont to the correct unicode value for that character to ensure proper transliteration use. 
So here is the finished set:
What a result! All the elegance of the original font, but now with all the dots needed to transliterate properly. The only drawback with using IndyFont is that there is no way to embed the original kerning, which would be quite an undertaking I know. But by keeping a good set of notes and using global changes you can easily over come this minor drawback to get the exact same kerning results as the original characters. Here is an example of the set in use:
I hope that you have gained some benefit and insight from this article. For an overview of available Arabic transliteration fonts please check my document on Scribd: https://www.scribd.com/document/227676611/Arabic-Transliteration-Fonts