Onenote Onetoc2

File extension onetoc2 is associated with Microsoft OneNote, an easy to use note taking and information management program from Microsoft Office system with which you can capture your thoughts and ideas in electronic notebooks, where you can easily organize, search, and share them. It appears that onetoc2 files contain saved table of contents. ONETOC2 is a file format used by Microsoft OneNote that contains information about ordering of various note sections. Removing ONETOC2 file will reset the sort order into default alphabetical sort. OneNote is a tool included in paid Office application package, but is also available as a free stand-alone application.

Notebooks on OneDrive use the latest OneNote file format. Users without OneNote 2010 or later can use the free web version or download a free version of OneNote from OneNote to access the notebook. For more information, see File format changes in OneNote 2016. Get OneNote for free! Works on Windows 7 or later and OS X Yosemite 10.10 or later.

What is ONETOC2?

Those who have worked with Microsoft OneNote application may have noticed the presence of .onetoc2 files in the notebook folder. Microsoft OneNote creates binary .onetoc2 file as Table of Contents for keeping an index about the ordering of different note-taking sections in a notebook. A notebook is a collection of section files that are stored in the same directory. The .onetoc2 file uses a collection of properties to specify settings such as order of sections within the notebook and the color of the notebook.

When you create a notebook in OneNote 2016, it’s automatically saved in the new 2010-2016 file format. You’ll need this format if you want all the features in OneNote 2016, like math equations and linked notes, to work properly.

ONETOC2 File Format

The .onetoc2 file format is represented as OneNote Revision Store File Format and is a collection of of structures that specify a revision store organized into cross-referenced object spaces, containing objects with property sets, and containing a transaction log to ensure file integrity across asynchronous writes. Complete specifications for the .onetoc2 file format are available online and can be referred to for development of applications.

File Structure

A revision store file MUST begin with a Header structure. The remainder of the file is partitioned into blocks of bytes, where the size and structure of each block is specified by the field that references it. A block is reachable if it is referenced by the Header structure, or if it is referenced by a field in another reachable block. Data outside the Header structure and any reachable blocks MUST be ignored.

All structures are aligned on 1-byte boundaries. All integers are signed unless otherwise specified. All fields are little-endian unless otherwise specified.

Header

The Header of .ONE file comprises of chunks that contain different unique ids and fields for representation of file information as follow:

guidFileType (16 bytes): A GUID that specifies the type of the revision store file. MUST be one of the values from the following table.

guidFile (16 bytes): A GUID that specifies the identity of this revision store file. SHOULD be globally unique.

guidLegacyFileVersion (16 bytes): MUST be “{00000000-0000-0000-0000-000000000000}” and MUST be ignored.

guidFileFormat (16 bytes): A GUID that specifies that the file is a revision store file. MUST be “{109ADD3F-911B-49F5-A5D0-1791EDC8AED8}'.

ffvLastCodeThatWroteToThisFile (4 bytes): An unsigned integer. MUST be one of the values in the following table, depending on the file type.

ffvOldestCodeThatHasWrittenToThisFile (4 bytes): An unsigned integer. MUST be one of the values in the following table, depending on the file format of this file.

ffvNewestCodeThatHasWrittenToThisFile (4 bytes): An unsigned integer. MUST be one of the values in the following table, depending on the file format of this file.

ffvOldestCodeThatMayReadThisFile (4 bytes): An unsigned integer. MUST be one of the values in the following table, depending on the file format of this file.

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References

Onetoc2 Onenote 2016

Symptoms

Assume that you try to open a folder that contains no .onetoc2 file in Microsoft OneNote 2010. In this situation, OneNote 2010 opens the folder as a notebook.

Resolution

To resolve this issue, follow these steps:

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1. Apply the hotfix package that is described in Microsoft Knowledge Base (KB) article 2523130. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

   2523130 Description of the OneNote 2010 hotfix package (onenote-x-none.msp): April 26, 2011

2. Enable the hotfix package. To do this, follow these steps:

   1. In Windows 7 or in Windows Vista, click Start, type regedit in the Start Search box, and then press ENTER.
      If you are prompted for an administrator password, type the password. If you are prompted for confirmation, provide confirmation.
      In Windows XP, click Start, click Run, type regedit in the Open box, and then click OK.

   2. Locate and then click the following registry subkey:
      

      HKEY_CURRENT_USERSoftwareMicrosoftOffice14.0OneNoteOptions

   3. On the Edit menu, point to New, and then click DWORD Value.

   4. Type EnableOpenFolderAsNotebook, and then press ENTER.

   5. Right-click EnableOpenFolderAsNotebook, and then click Modify.

   6. In the Value data box, type 0, and then click OK.

   7. Exit Registry Editor.

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Now, if no .onetoc2 file is found in the folder, OneNote 2010 opens a single section. If a .onetoc2 file is found in the folder, OneNote 2010 opens the .onetoc2 file as a notebook.
Note Additionally, this update improves performance and synchronization against SharePoint servers.