Microsoft Office File Extensions

OK, this might seem like an article way out of date, but you’d be wrong. Sure, I’m going to discuss Microsoft Office formats from more than five years ago, but you’d be surprised at how often we get asked about the new (!) Office file formats. So here’s the scoop – the one that uses a trowel, not a snow shovel scoop.

When Microsoft^® released Office 2007, they introduced a new file format in their various programs that was based on Open XML. (Extensible Markup Language – do you really want more detail on that? We didn’t think so.) Microsoft’s new file format applies to Office products 2007 and beyond. The new file format was incompatible with previous versions until Microsoft released “converters” for older versions of the software, so no need to fret now – you can download the converters and all will be well with your world. (OK, maybe just a little piece your world will be well, but a little piece is better than none.)

To distinguish files using the new file format from the previous format, Microsoft added an x or an m to the extension –

What’s the difference between the x and the m?

• The x signifies an XML file with no macros
• The m signifies an XML file that does contain macros

What’s it mean to you?

• If your file has macros, you will need to save using the m extension.
• Yes, files are backwards compatible, but you will need to download file converters for earlier versions of Office.

Why’d they do it? It’s a security thing largely. They say it makes for smaller files, too but I haven’t found that to be true.

Aren’t you glad you asked?