Based on contributions from major browser developers, the updated Bidirectional Algorithm and five new bidi format characters will improve the display of text for hundreds of millions of users of Arabic, Hebrew, Persian, Urdu, and many others. The display and positioning of parentheses will better match the normal behavior that users expect. By using the new methods for isolating runs of text, software will be able to construct messages from different sources without jumbling the order of characters. The new bidi format characters correspond to features in markup (such as in CSS). Overall, these improvements also bring greater interoperability and an improved ability for inserting text and assembling user interface elements.
The improvements come with new rigor: the Consortium now offers two reference implementations and greatly improved testing and test data.
In a major enhancement for CJK usage, this new version adds standardized variation sequences for all 1,002 CJK compatibility ideographs. These sequences address a well-known issue of the CJK compatibility ideographs — that they could change their appearance when any process normalized the text. Using the new standardized variation sequences allows authors to write text which will preserve the specific required shapes of these CJK ideographs, even under Unicode normalization.
Version 6.3 includes other improvements as well:
- Improved Unihan data to better align with ISO/IEC 10646
- Better support for Hebrew word break behavior and for ideographic space in line breaking