A file with a .odf extension is a document having mathematical equations, macros, and formulas. It is created with Apache OpenOffice Math program that is used for creating Math formulas which can then be saved to disc or included in other documents. These files are created and saved based on the OASIS OpenDocument standard which is an open standard file format for spreadsheets, charts, presentations, and word processing documents using ZIP-compressed XML files. ODF files can be opened with applications such as OpenOffice Math and LibreOffice Draw.
ODF File Format - More Information
ODF files are zip-compressed XML files which means that all the details about the contents of an ODF file are organized in XML files which are then combined as a ZIP archive. Anyone can rename the file to .zip and extract its contents using a decompression utility, such as WinZIP.
Include ODF File in Other Applications
ODF files can be opened in the OpenOffice Math application. However, these files can also be embedded in other documents such as Calc or Impress. Similar to Microsoft Office applications, when an ODF file is inserted in other documents, it is imported as an object that can be double clicked for editing in the parent application.