How to identify an ODF file?

Question

I need to be able to identify that a given file is an ODF file based on the contents of the file, and not on the file's extension.

ODF files are really a collection of XML files in a zip container, which means that I cannot use the file's magic number as it will just indicate that it is a zip file.

So what I'm really asking is are there any files that are required to be present in an ODF container? If so the presence of that file in a zip container indicates that it is likely to be an ODF file, and the absence of that file indicates that it definitely is not an ODF file.

Answer 1

Why not check out the ODF Technical Specification? The mimetype file listed there would probably be an ideal way to check (just look for the vnd.oasis.opendocument string in the mimetype).