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MTE Explains:Common Word Processing File Formats

If you've ever tried to save a document for use on another computer, you'll probably have been overwhelmed by the number of file formats you can choose from. Microsoft Office comes with a dazzling array of formats that you probably won't use:for the average person, Office's default settings are hard to beat. Size ComparisonConclusion

Anyway, you will also have wondered what these other file types are for. In this article, we'll cover many document-related formats that can be changed where possible.

Currently, .docx is the default file format in Microsoft Word and has been since Office 2007. Opening a .docx file in Office 2003 will force it to open in "compatibility mode". It is a fundamentally different format from its predecessor, based on Extensible Markup Language (XML) and .zip compression technologies. Therefore, file types are expected to be smaller. Corrupted documents can also recover part of their content.


The predecessor to the .docx file format, it has long been a mainstay of word processing. It was a de facto standard before .docx was released; even the latest versions of Office allow you to save files in this format. Thus, it remains popular and is the best way to maintain compatibility with older versions of Microsoft Office.


Described in Word as a “macro-enabled Word document,” the format originated with Office 2007. If you want a macro to work, the document must be saved in .docm format. Saving it in another format will not allow it to work. For the average computer user, this is a rare format to encounter. We strongly recommend that you scan all .docm files, as a macro can infect a computer with a virus.


You may have already assumed that based on the "x" in the file format, .dotx is a newer file format. This assumption is absolutely correct. This file serves as a template, allowing you to maintain a consistent appearance across different documents. The "x" format is newer and offers smaller file sizes due to XML and .zip, much like the .docx format.


The predecessor of .dotx, this format serves as a template for other documents. If you've spent time studying how a document looks, you might want to save it as a template for the future. In the past, .dot was the only way to do this. Nowadays it has been largely superseded, but it is the last model that Office 2003 can accept.


Like .dotx, this template format appeared with the release of Office 2007. The “m” at the end of the extension indicates that the template is macro compatible. While this isn't likely to be a major boon for day-to-day computer use, it could come in handy in corporate settings.


Called "OpenDocument Text" in current versions of Microsoft Office, .odt is an open standard for text documents. This means that most, if not all, word processors should be able to support it. For example, a document saved in this format with Office should appear identical in OpenOffice, LibreOffice and other free office suites. Like the latest generation of Office file formats, it relies on XML to achieve its goals. Note that, according to the source, .fodt is sometimes used as a file format.

When we attempted to save a document in this format, Word generated the following error message, although it managed to save the document successfully.


A file format unique to AbiWord, it somehow proves a limitation for other office suites. Opening an AbiWord file in Microsoft Office produces a "DTD" error, which occurs with XML files (more explanation available here). Subsequently, it seems likely that .abw is an XML-based format, but not fully compatible with other word processors. Thus, we suggest that you use this type of file only if you know that you will be accessing your documents via AbiWord.


Although this is not an exhaustive comparison, we decided to try to determine which format offers the smallest file size among those already described. For this test, we used Project Gutenberg's plain text copy of The Prince, by Niccolo Macchiavelli and saved it in a variety of formats. Except for the .abw file, all formats were saved using Office 2013.

The .odt file format resulted in a particularly nice file size, even smaller than Microsoft's .docx format. AbiWord's .abw file looks relatively gargantuan, bloating up to more than ten times the size of Microsoft's outdated .doc format.


There you have it:more than you ever imagined you knew about document file formats. If you've noticed the frequent references to Microsoft's "x" file formats and wanted to learn more, you'll be happy to know that they have a dedicated Wikipedia page. Although this is a very technical overview, the page provides insight into using XML in other Office programs, including Excel and PowerPoint.