Why doesn't Document Metadata Cleaner supports docx, xlsx and pptx files
Microsoft switched to XML-based file formats in Office 2007, and added an 'x' to the file extensions to differentiate from the previous, incompatible formats.
These new file formats no longer contain metadata like the previous doc, xls and ppt did, so Document Metadata Cleaner does not open or process dox, xlsx and pptx documents.
For more information about this new file format, please read Microsoft's "Introduction to new file-name extensions":
http://office.microsoft.com/en-us/help/introduction-to-new-file-name-extensions-HA010006935.aspx
