What should I know about the Open XML file formats? Microsoft Office Word 2003 and earlier versions have always used two file types: one for documents (.doc) and another for templates (.dot). Word 2007 will use four different file types: .docx, .dotx, .docm, and .dotm (the x stands for XML and the m for macro). Word documents and templates no longer contain macros or code, a safety mechanism that prevents an attacker from adding hidden code in a document. So when you save a Word 2007 document that doesn't have associated components (e.g., macros or comments), you'll see a .docx (for a document) and .dotx (for a template) file. However, if you used a macro (or another component), you must save the file as a macro-enabled document or template (i.e., .docm or .dotm), otherwise the macro won't work. To do so, from the Save dialog box, use the Save As Type drop-down list to select the document type. Developers can programmatically access a document's components to enable data mining, document creation from disparate sources, and document manipulation. For example, you could change a corporate logo in a group of documents by using an XML editor. You can also generate Office 2007 documents on a server without having to install the client applications—a big plus for custom applications (custom app developers will love being able to generate Office documents on-the-fly on servers). The formats for the new Office 2007 documents will be published and available under the same royalty-free license as the Microsoft Office 2003 XML Reference Schemas. Microsoft provides more information for developers about the technologies used in Office 2007 at http://msdn.microsoft.com/office/future/tools/default.aspx.