Unicode Nearly Plain-Text Encoding of Mathematics, Version 3 (Unicode Technical Note #28) is now posted. The differences between Version 1 and 2 of that paper are largely cosmetic, but there were enough changes in Version 2 to merit a new number. Version 2 is mostly implemented in Microsoft Word 2007, where it is referred to as the “linear format”. Typing the linear format into a Word 2007 math zone results in “formula autobuildup”, that is, automatic conversion to the built-up format of expressions as their syntax becomes unambiguous.
The new features added in Version 3 are identified as such. They are mostly implemented in the Microsoft Office 2010 applications Word, PowerPoint, Excel, and OneNote. Typically the new features offer convenience over ways defined in Version 2, and the Version 2 syntax remains valid in Version 3. The additions were often inspired by [La]TeX. Examples of simplified input are \choose for binomial coefficients, \cases for alternative definitions, \pmatrix for parenthesized matrices, \middle to define a custom character as a bracket separator, a simpler prescript notation, \root n\of x notation for nth roots, equation alignment, size overrides, and simple negated operator input. The section Version Differences has hyperlinks to where these additions are documented. There are also numerous cosmetic changes along with lots of internal links to facilitate navigation.
If you use Microsoft Office math zones, please read Section 2. It’s a quick read. The knowledge so gained makes it easy to enter simple mathematical expressions into Word 2007/2010, PowerPoint 2010, OneNote 2010 and Excel 2010. Section 3 discusses how to enter more complicated expressions.