Open XML Format
When you create a presentation, template, or show in PowerPoint, PowerPoint
automatically saves the presentation, template, or show in the Open XML Format. This file format differs from the format used by PowerPoint 2004 for Mac
or earlier and PowerPoint 2003
or earlier. The sections below describe the file formats that you can use to share a PowerPoint
presentation, template, or show people who use other versions of PowerPoint.
Some items that were created using new features in Office for Mac 2011
might behave differently when the document is saved in the file format used by Office 2004 for Mac
or earlier. Use the Compatibility Report to avoid using new Office
features that might behave differently with earlier versions of Office.