Risks from comments and tracked changes

Comments, tracked changes, collaborative editing information, and annotations can reveal creators, editors, organizations, and original wording.

Document files may retain not only body text, but also comments, tracked changes, editor names, and editing times.

Office documents, PDFs, and collaborative editing documents require particular care.

When sharing a document anonymously, removing names from the body text is not enough if comments or tracked changes still contain creators, editors, organization names, or traces of exchanges.

This article organizes how comments and tracked changes relate to anonymity, and what to check before publication.

What are comments and tracked changes?

Comments are notes or remarks attached to specific parts of a document.

Tracked changes and revision history record who changed which part and when.

These may remain inside the file even when they are hidden on screen.

"Not visible" and "deleted" are different.

Why this relates to anonymity

Comments and tracked changes show the process by which a document was made.

For anonymity, that process becomes a strong clue.

For example, when sharing internal materials anonymously, even if a department name is removed from the body text, a supervisor's name or team name left in a comment narrows the possible source.

In reporting materials, comments and revision history may allow a source, editor, or pre-publication exchange to be inferred.

Comments and history are places people are more likely to overlook than the body text.

That is exactly why they must be checked before publication.

Original information can remain in tracked changes

The especially dangerous point about tracked changes is that information you thought you deleted can remain in the history.

Even if a name has been removed from the body text, displaying the change history may reveal the original name.

The same applies to addresses, department names, names of people involved, timelines, and internal terms.

Documents edited for anonymization require particular attention to tracked changes.

That is because the editing process itself contains the information you wanted to hide.

What to check before publication

Before publishing a document, check the following items.

In Office documents, a document inspection feature may be available.

However, even if you use an inspection feature, do not treat that alone as complete.

After removal, check again by another method.

Cautions for collaborative editing documents

In collaborative editing documents, not only the file itself but also service-side history becomes a problem.

Who edited it, who commented, who it was shared with, and which account opened it may remain on the service side.

Exporting a file from a collaborative editing service does not mean the service-side history disappears.

When thinking about anonymity, look separately at the contents of the file and the history that remains on the cloud side.

Deleting comments is not enough

Even if you delete comments, tracked changes, creator information, filenames, and cloud history may remain.

Deleting comments is necessary work.

However, document anonymization requires checking multiple layers.

Instead of thinking "I deleted the comments, so it is fine," you need the mindset of rebuilding the whole document as a file for publication.

Check even after converting to PDF

Documents are sometimes converted to PDF to remove comments and tracked changes.

PDF conversion is useful in some situations, but it is not universal.

Annotations, creator information, hidden text, and embedded files may remain inside the PDF.

Also, the conversion process may newly attach the creator application name or creation time.

For that reason, even after converting an Office document to PDF, check it again as a PDF.

Review content too for high-risk documents

Even if comments and change history are deleted, the body content itself may indicate the source.

Topics known only to people who attended a specific meeting, abbreviations used only by a specific department, materials distributed only to a small number of people, and detailed timelines are clues separate from metadata.

For whistleblowing and reporting materials, removing metadata from a document is not enough.

Check from a third-party perspective whether someone could infer who was able to know the content.

The idea of rebuilding a file for publication

When a document contains many comments and changes, it may be safer to rebuild a file for publication than to clean the original file directly.

For example, you can move only the necessary body text into a new document, generalize proper nouns, and create a publication PDF with no comments or history.

However, the new document may also receive a creator name and creation time.

For that reason, after rebuilding it, recheck the metadata and filename.

For anonymity, separating the work of processing the original from the work of creating a file for publication makes checking easier.

Summary

Comments and tracked changes show the document creation process.

Even if names and place names are removed from the body text, anonymity weakens if they remain in comments, tracked changes, annotations, or creator information.

Especially in whistleblowing, reporting materials, and collaborative documents, editors, departments, editing times, and original wording become strong clues.

Before publication, check comments, tracked changes, creator information, annotations, and hidden elements.

PDF conversion is not the end. After converting to PDF, recheck both the file's metadata and its appearance.

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• Metadata —Metadata in Office files
• Whistleblowers —Author and organization information left in document files
• Metadata —Removing image metadata
• Metadata —How Images Can Break Anonymity
• Metadata —Risk of Identity Inference From Backgrounds, Reflections, and Text in Images
• Metadata —Metadata left in submissions and file sharing