It was my understanding that an ODT file was a ZIP file that contains various files that comprise an OpenOffice / LibreOffice document. However, I was running a script to search through these files when I noticed that I was getting an error from some of my ODT files about an end of central directory signature not being found. When I looked at these files I discovered that they were in fact plain XML.
Is this expected? What determines whether ZIP or XML is used? Is there some mechanism I can use to easily determine which type of file an ODT file is, aside from simple checking if unzip fails?