The following resources can be used as references: Office File Formats (Not including OOXML formats) https://msdn.microsoft.com/en-us/library/cc313118(v=office.12).aspx Office Open XML File Formats (ECMA-376, ISO/IEC 29500) http://www.ecma-international.org/publications/standards/Ecma-376.htm https://www.iso.org/committee/45374/x/catalogue/
If you don’t have MS Office installed, you can try their online service to see the attached file to see what it should be looks like. Steps to use: 1. Open a bug report from here. 2. Right click an attachment link, then select “Copy link adress”. Note: the attached file must be MS Office format, and not “Details” link at its right side. 3. Open http://www.officewebviewer.com 4. Paste the URL into input box, then click Create URL. 5. Click “preview in a new window”.
From here we can see how does Microsoft did in their Office suite. https://docs.microsoft.com/en-us/openspecs/office_standards/ms-offstandlp/d5784a8b-7070-466b-befa-b7bf3724c6f0