There is only one file type that uses the .ODO extension:
Online Operating System Write Document
Document created using Write, an Online Operating System (OOS) program used to create text documents; contains text, page formatting, and other document objects and styles; used to store Write documents within the OOS environment.
OOS is an application that emulates a Windows-like operating system environment within a Web browser. It allows users to customize personal desktop environments and share files with other users.
Updated: February 6, 2010