How do I save in ODF Formula ODF ?
The abbreviation “ODF” is used with meanings in this context:
-1- “Open Document Format for Office Applications (OpenDocument)”, the overall term for the open file formats for office applications approvd by OASIS (currently V1.2) which might better be abbreviated by OD only.
-2- The default file extension used for document files exclusively containing formulas and saved in compliance with the above mentioned specification.
If you create a “pure” formula document with LibreOffice ODF is the only format amd .odf is the only default extension you gt offered by ‘Save As…’.
Different document classes are saved in their respective native formats with the respective default extensions also if they contain embedded formulas.
If you force a misleading extension upon a ODF compliant file, LibreOffice will open it with its the appropiated modules anyway.