This setting lets you suppress the Restore button in the previous versions property page when the user has selected a previous version of a local file, in which the previous version is stored on a backup.
If this setting is enabled, then the Restore button will be disabled when the user selects a previous version corresponding to a backup.
If this setting is disabled, then the Restore button will remain active for a previous version corresponding to a backup. If the user clicks the Restore button, then Windows will attempt to restore the file from the backup media.
If this setting is not configured, it will default to disabled - the Restore button will be active when the previous version is of a local file and stored on the backup.