Files with DOTX extension are template files created by Microsoft Word to have pre-formatted settings for generation of further DOCX files. A template file is created in order to have specific user settings that should be applied to subsequent flies created from these. These settings include page margins, borders, headers, footers, and other page settings. Such templates are used in official documents such as company letterheads and standardized forms.
The DOTX file format was introduced with the release of Microsoft Office 2007 to replace the binary DOT file format, but is supported by higher versions as well. Microsoft Word by default opens every new document based on normal.dot file. If modified, all the new files created will result in same settings as from the template file. In Microsoft Word 2007, the DOT file format has been replaced with Office OpenXML based DOTX file format.
It was in the early 2000 when Microsoft decided to go for the change to accommodate the standard for Office Open XML. Documents, of different types, under this new Standard were identified by appending “X” in their extensions, where “X” being for XML. By 2007, this new file format became part of Office 2007 and is carried on in the new versions of Microsoft Office as well. The new file type has added advantages of small file sizes, less changes of corruption and well formatted images representation.
File Format Specifications - More Information
The DOTX file format follows the same DOCX structure based on Office OpenXML file format. Contents of a DOTX file format can be viewed by renaming it to ZIP and opening the archive using any supporting utility. The MS-DOCX specifications define the Office OpenXML file format details for DOCX file format for developers' reference.