This policy setting controls whether PowerPoint 2007 users can open PowerPoint presentations that were saved in formats used in versions of PowerPoint older than PowerPoint 97.
If you enable this policy setting, PowerPoint 2007 users will not be able to use converters to open presentations saved in versions of PowerPoint older than PowerPoint 97.
If you disable or do not configure this policy setting, file formats are not blocked.
Note - See Plan block file format settings in the 2007 Office system (http://r.office.microsoft.com/r/rlidGroupPolicyBlockFileForm2?clid=en-us) in the 2007 Office Resource Kit for more information about using Group Policy to manage and enforce file format requirements. Also, see the "File Block Technology" section in Chapter 4 of the 2007 Microsoft Office Security Guide for information about the Microsoft Office Isolated Conversion Environment (MOICE), which provides another method.