[alreq] Section on overlapping letter glyphs

behnam has just created a new issue for https://github.com/w3c/alreq:

== Section on overlapping letter glyphs ==
In various styles of Persian/Arabic script, glyphs of letters may 
overlap intentionally. I think we need to cover this script feature 
under letter positioning section.

An example from Zarnegar 5.2 Catalog 
(http://sinasoft.com/Downloads/zarnegar5.2/catalog/Zar52Cat.pdf): on 
the right we have "before repositioning" and on the left we have 
"after repositioning".

![image](https://cloud.githubusercontent.com/assets/37169/21593581/6334f6fc-d0de-11e6-8c37-915415aee839.png)

We should also note that sometimes, mostly because of bad (mainly 
practical) font glyph data, *unintentional* glyph overlap may occur. 
This unintentional behavior is different from the intentional design 
mentioned above, and a shaping engine may decide to be smart about 
this and resolve it somehow.



Please view or discuss this issue at 
https://github.com/w3c/alreq/issues/87 using your GitHub account