Unicode Arabic Mark Rendering UTR #53 Now Published

The combining classes of Arabic combining characters in Unicode are different than combining classes in most other scripts. They are a mixture of special classes for specific marks plus two more generalized classes for all the other marks. This has resulted in inconsistent and/or incorrect rendering for sequences with multiple combining marks since Unicode 2.0.

The Arabic Mark Transient Reordering Algorithm (AMTRA) described in UTR #53 is the recommended solution to achieving correct and consistent rendering of Arabic combining mark sequences. This algorithm provides results that match user expectations and assures that canonically equivalent sequences are rendered identically, independent of the order of the combining marks.

The concepts in this algorithm were first proposed four years ago by Roozbeh Pournader. We are pleased it has now been published as an official Technical Report.

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