Styles, Doc Defaults, Style Sets, and Themes
http://blogs.msdn.com/microsoft_office_word/archive/2008/10/28/behind-the-curtain-styles-doc-defaults-style-sets-and-themes.aspx

Microsoft
2008

Abstract:

In all previous versions of Word the Document Defaults were hardcoded into Word. That is, you couldn't change them. This means that the way you would change the default properties applied to your documents would either be to change the Styles within the Template used to create the document, or to write a macro that went through all documents and updated the properties defined by the Normal Style (the paragraph Style applied to text by default). In Word 2007, you can certainly still do the former, but should know the following before you do the later: by default, the Normal Style is empty.