There is only one file type that uses the .ONETOC2 extension:
Microsoft OneNote Table of Contents File
Index file created by Microsoft OneNote, a program used for personal journaling and note taking; stores information about the ordering of different note-taking sections; used for organizing the collection of notes in the notebook.
If the ONETOC2 file is deleted, OneNote will display the notebook sections in alphabetical order, which the user can manually reorder.
|Microsoft OneNote 365||Free|
Updated: March 7, 2010