How does IDNA2008 improve handling of Arabic and Hebrew (BIDI)?
Arabic and Hebrew writing systems are known as bidi (bidirectional) because text runs from right-to-left and numbers (or embedded Latin characters) from left-to-right. IDNA2008 does a better job of restricting labels that lead to “bidi label hopping”. This is where bidi reordering causes characters from one label to appear to be part of another label. For example, “B1.2d” in a right-to-left paragraph (where B stands for an Arabic or Hebrew letter) would display as “1.2dB”. For more information, see the Unicode bidi demo. While these new bidi rules go a long way towards reducing this problem, they do not completely eliminate it because they do not check for inter-label problems.
