# Extract Deleted Text Marked by Tracked Changes

The revision tracking feature in applications—such as Microsoft Word's Track Changes—marks changes to a document (typically, strikethrough for deleted text and underline for inserted text) and tracks each change by reviewer name and date.

If revision tracking was enabled when text was deleted from a source document, you can configure Filter to extract the deleted text. Filter does not extract the reviewer name and revision date.

To extract deleted text from a document and include it in the filtered output

1. Create a `Session` object.

2. Enable revision tracking by calling `revision_marks(true)` on the `Configuration` object.

3. Call `filter()` on the `Session` object.

See The Session Class for more information.

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