FWIW the 2007+ office file extensions are all more than 3 characters (e.g. ACCDB, ACCDT, DOCX, DOCM, DOTX, DOTM, XLAM, PPTX, PPTM, POTX, POTM, PPAM, PPSX, PPSM,

FWIW the 2007+ office file extensions are all more than 3 characters (e.g. ACCDB, ACCDT, DOCX, DOCM, DOTX, DOTM, XLAM, PPTX, PPTM, POTX, POTM, PPAM, PPSX, PPSM, SLDX, SLDM, XLSX, XLSM, XLTX, XLSM, XLSB)