Indiana Code Title 3. Elections § 3-11-15-23

Sec. 23. To attain a measure of integrity over the process, the electronic voting systems must also maintain an image of each ballot that is cast, such that records of individual ballots are maintained by a subsystem independent and distinct from the main vote detection, interpretation, processing, and reporting path.  The electronic images of each ballot must protect the integrity of the data and the anonymity of each voter, for example, by means of storage location scrambling.  The ballot image records may be either machine-readable or manually transcribed, or both, at the discretion of the vendor.