Notes about the XLSX file extension:
To open this file type, a required software must be installed. Without it you only see a Windows message "The following file cannot be opened
" (Windows 7) or "How do you want to open this file?
" (Windows 10) if you double-click the file. There click on "More apps"
and choose a suitable software to view such files on your PC or from email attachments.
The XLSX file type is primarily associated with 'Excel' by Microsoft Corporation.
This is the new format for Microsoft Office documents.
It is a combination of XML architecture and ZIP compression for size reduction.
Microsoft promises the format will be open (published for anyone to use) and prior versions of Office, using components provided by Microsoft for Office 2000, XP, and 2003 will be available to perform document conversion. Remember that these are promises by Microsoft. We have yet to see the actuals. This format is not the same as the OpenDocument standard, also an XML-based standard being developed as a true open standard (see the OpenDocument Fellowship for more information).
Detailed information for file extension XLSX:
Primary association: Excel
Mime type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheetIdentifying characters
Hex: 50 4B 03 04 , ASCII: PK
'Identifying characters' used on FILExt.com are
provided by Marco Pontello from his TrID database
To change file associations press Windows Key
and then Apps and Features
> Default apps
> Choose default apps by file type
Invalid file associations could be the result of underlying issues within your Windows PC.