ODF is an ISO standardized format for office documents. For spreadsheets, it uses the .ods extension; the other two extensions are .odt for textual files and .odp for presentations. ODF files are essentially XML files that comply with the XML schema defined in ISO / IEC 26300: 2006. The last revision dates from 2015.
The advantage of ODS is that it is an open standard that can be processed by multiple applications. Metadata can be added in the form of RDF to later versions of ODF. You can add metedata up to the level of cells, in the case of spreadsheets. Examples of office suites that use ODF include OpenOffice and LibreOffice. MSExcel files can also be saved as ODS. There are various software libraries that can be used to program ODF programmatically.

Media type
The media type of ODS files is application/vnd.oasis.openocument.spreadsheet and application/vnd.oasis.openocument.spreadsheet-template for templates.

Also see
Planning for Library of Congress Collections: https://www.loc.gov/preservation/digital/formats/fdd/fdd000439.shtml

ODS is a preferred format for the Spreadsheets file type.