From Microsoft Office 2007 onwards, the core output format of MS Powerpoint has been based on the Office Open XML (OOXML) file format. The ISO standard for OOXML is ISO/IEC DIS 29500. An OOXML file format consists of a compressed zip archive that is designated according to which file type it is. Further detail on OOXML can be found within fmt/189 - Microsoft Office Open XML.
This format can be identified via a container signature in DROID version 6 or later. The PRONOM database cannot currently represent container signatures.
Details: File format summary
: detailed report on file format 
Microsoft Corporation
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