The SHADOW folder, at the root of the workspace, contains previous versions of the documents that exist in the workspace at the time of backup. If you select the SHADOW folder to include in a workspace backup, you can have access to the previous versions of the documents in the workspace. However, you cannot restore the previous versions directly back into the workspace. You must restore them to an alternate location and then manually copy them into the workspace.
To restore previous versions of documents from workspace backups
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Redirecting restored SharePoint 2001 workspace data to a file path