Bidirectional layout support

Mathematical notation is mostly consistent around the world. However, there are some notations that differ depending upon the language/locale such as "." versus "," for a decimal separator and "tan" (English) versus "tg" (French) for the tangent function. For people who want to produce language-independent MathML, content MathML smoothes over these differences and presentation MathML allows these specific notations to be encoded.

In Arabic countries, mathematical notation is written right-to-left using the same alphabetic characters. MathML 3 now makes it possible to encode right-to-left notations in presentation MathML. MathML 3 adds a dir attribute to control whether layout is left-to-right or right-to-left (see Section 3.1.5 of the MathML 3 recommendation for details). MathML 3 also introduces some mathvariant values for handling different styles of Arabic characters (see Section 3.2.2).

Here are two examples of Arabic math that use right-to-left notation (note: numbers are still left-to-right in Arabic math notation):

Square root	Long division