we have a mechanical check for the tickets [ballots], while the ticket is also a check upon the register [mechanical vote counter]." This check is only effective, of course, if there is an audit to compare the paper and mechanical records. The idea of creating a parallel paper trail for a direct-recording voting mechanism remained dormant for a century, until it was rediscovered by Rebecca Mercuri, who suggested essentially the same idea in 1992. The Mercuri method, as some have called it, was refined in her Ph.D. dissertation in October 2000; in her final version, the paper record is printed behind glass so that the voter may not take it or alter it. The first commercial voting systems to incorporate voter verifiable paper audit trail printers were the Avante Vote Trakker and a retrofit to the Sequoia AVC Edge called the VeriVote Printer. Avante's system saw its first trial use in 2002, and in 2003, the state of Nevada required the use of VVPAT technology statewide and adopted the Sequoia system. It is notable that, in Avante's design, the shield preventing the voter from taking the paper record was an afterthought, while in Sequoia's design, the paper record for successive voters were printed sequentially on a single roll of paper. Application Various technologies can be used to implement a paper audit trail. Attachment of a printer to direct-recording electronic (DRE) voting machines that print paper records stored within the machine. Such designs usually present the record to the voter behind a transparent surface to enable a voter to confirm a printed record matches the electronic ballot. The records can be manually counted and compared to the electronic vote totals in the event of a dispute. The solution linking electronic ballot images and the voter-verified paper record with randomly generated unique voting session identifier is covered by patents issued and pending. Attachment of a printer to DRE voting machines that print paper records on special paper with security features. The printed page contains both a plain text record and a simple barcode of the voter's selections. This page is the official ballot that is then fed through a scanner into a locked ballot box so that all originals are saved in case of the need for a recount or audit. The electronic record from the DRE is compared with the barcode scanner record and in case of any discrepancy, the paper