I need to send a document to the Inland Revenue and they will only accept a document in odf with the extension odf. But LibreOffice saves with the extension as fodt, how do I save with the extension in ODF .
How do I save the file, as it does not show in the list offered? There are many other extensions like odt, ott fodt etc.
Either their requirement is bad, or you don’t understand it correctly. Normally, it isn’t an extension what matters, but the file format. Thus, which file format do they require?
I doubt that any governmental agency would require .odf files: there produced by the Math component of LO. What would they do with a tax-payer-provided mathematical formula?
Read @gabix’s comment and explain as accurately as possible what is required.
I take it your document is produced in LO’s Writer. If so, the “Open Document Format’s” (odf’s) extension should be .odt. So select “File” > “Save As”, open the “Save as type” list and choose “ODF Text Document (.odt) (*.odt)”.
Appendix B of LO 5.2’s “Getting Started” user guide introduces open document format and explains the extensions used in the other LO applications. You can download the guide free from the Document Foundation’s documentation pages (Getting Started Guide | LibreOffice Documentation - Your documentation for LibreOffice).
I take it that your reference to the Inland Revenue means you are based in the UK, so you might also like to look at the UK’s official guidance for Civil Servants (it is quite readable!). You can download it free from the Cabinet Office website (https://www.gov.uk/government/collections/open-document-format-odf-guidance). And there is a lot more Cabinet Office advice as well from this site, the guidance on meeting user needs (https://www.gov.uk/government/publications/open-document-format-odf-user-needs) might be useful).
I don’t think you have correctly understood what Inland Revenue want – but you should supply the text (or a screenshot) of the instructions requiring an ODF extension.
The previous answer provides some very helpful links – and they make clear that what is needed is a document in ODF format, not a document with an ODF extension. Their own “ODF” document types includes the *.ods spreadsheet in ODF format, for example:
And note that this is the expected file extension for spreadsheets (not ODF):
