The version included in Mac OS X v10.6 added automatic spelling correction, support for data detectors, and text transformations.
The version included in Mac OS X v10.5 added read and write support for Office Open XML and OpenDocument Text. The version included in Mac OS X v10.3 added the ability to read and write documents in Word format, and the version in Mac OS X v10.4 added the ability to read and write Word XML documents. It also has access to the operating system's built-in spell-checking service. TextEdit uses the Cocoa text system to read and write documents in Rich Text Format (RTF), Rich Text Format Directory, plain text, and HTML formats, and can open (but not save) old SimpleText files. TextEdit replaced the text editor of previous Macintosh operating systems, SimpleText.
