The combining classes of Arabic combining characters in Unicode are a mixture of special classes for specific marks plus two more generalized classes for all the other marks. For many years this has resulted in inconsistent rendering for sequences with multiple combining marks such as:
The algorithm described in this UTR provides a method to reorder Arabic combining marks in order to accomplish the following goals:
- The inside-out rendering rule will display combining marks in the expected visual order.
- Ensure identical display of canonically equivalent sequences.
- Provide a mechanism for overriding the display order in exceptional cases.
For information about how to discuss this Public Review Issue and how to supply formal feedback, please see the PRI #359 page.