When you work in Microsoft Office, all your PowerPoint presentations, documents, and worksheets get saved in XML file format by default. Usually, there a letter “x” or “m” which are added to your familiar file extension. The letter “x” indicates that your XML file contains no macros, and the opposite is indicated with the letter “m”. Let’s say, you have saved your file in MS Word, you can see the name of this file is .docx. You get this file extension by default instead of a common .doc extension.
Exactly the same change will happen when your file gets saved as the template. The extension for file templates also has “m” or “x” at the end of the file name. When your template has macros/code, it is recommended to save the file in XML format and you will have the letter “m” indicating macros.
Below, you will find a list of file name extensions which you get by default while working in PowerPoint, Excel, and Word.
.docx – documents
.docm – documents which are macro enabled
.dotx – templates
.dotm – templates which are macro enabled
.xlsx – workbooks
.xlsm – workbooks which are macro enabled
.xltx – templates
.xltm – templates which are macro enabled
.xlsb – workbooks which are non-XML binary
.xlam- add-in which are macro enabled
.pptx – presentations
.pptm – presentations which are macro enabled
.potx – presentation templates
.potm – presentation templates which are macro enabled
.ppam – add-ins which are macro enabled
.ppsx – shows
.ppsm – shows which are macro enabled
.sldx – slides
.sldm – slides which are macro enabled
.thmx – Microsoft Office themes