Securiosa: Deconstructing an ES&S ExpressVote Paper Record

General Structure

Figure 1: ES&S ExpressVote paper record (2016)

The paper record used by the ExpressVote is 4.25 inches wide and 14 inches long—half of a legal-size sheet of paper. The paper record is made of thermal paper which a thermal printer inside the ExpressVote marks on using heat (not ink). It is technically referred to as an “ExpressVote Activation Card.”
The paper record has a diagonal notch in the upper right corner which is used to ensure that the thermal paper is inserted with the correct side facing up to allow thermal printing.
Header information may include a precinct barcode, a description of the election, the date, and other general data. The header information may be printed by the ExpressVote or pre-printed by a printer attached to an electronic poll book.
The ballot style is encoded in a 2.75-inch barcode at the top which decodes to a 28-digit number. The ballot style determines which contests and candidates are referenced, and it typically varies for each precinct.
Ballot selections are encoded as smaller one-inch barcodes in three columns (“selection barcodes”). (See Figure 1.)
All barcodes are in Code-128 format. The 128C character set is used so that numbers are encoded in pairs and the barcodes are shorter.
If the barcodes do not divide evenly by three, the remaining columns are left blank.
If the voter does not make a ballot selection in a contest, no selection barcode will be printed for the contest and the ballot summary will display “No selection”.

Encoded Data

ES&S ExpressVote paper record shown on the left. Decoded values of barcodes and how decoded values correspond to candidate names in the summary shown on the right.

Figure 2. ES&S ExpressVote paper record (2018)

Selection barcodes contain six-digit numbers which correspond to candidates or other ballot selections. (See Figure 2.)
Selection barcodes are not printed in the same order as the human-readable summary. The order is an artifact of how they are stored and processed by the code.
The values encoded in selection barcodes are numerical representations of the coordinates of the ovals on a mark-sense, pre-printed ballot (a.k.a. hand-marked paper ballot). Jurisdictions often scan both hand-marked ballots and ExpressVote-generated paper records on the same optical scanner (e.g. an ES&S DS200 optical scanner). The scanner may either detect marked ovals on the mark-sense ballot to generate a list of coordinates or the barcode may be scanned to generate a list of the coordinates. Each set of coordinates is looked up in the ballot definition file in order to assign a vote to a particular candidate.

Positions on a Mark-Sense Ballot Grid

ES&S mark-sense ballot (2018) with grid overlay. — Figure 3. ES&S mark-sense ballot

ES&S mark-sense ballot (2018) with grid overlay and numbered ovals. — Figure 3. ES&S mark-sense ballot

The ovals on a mark-sense ballot are organized into a grid. Each row in the grid is 0.5cm tall. Each column of the grid is 0.8cm wide. The ballot has “timing marks” which appear as a dotted border around the ballot and which match the height and width of the grid. (See Figure 3.)
The coordinates of any oval can be defined as a six-digit number which follows the pattern CCRRSP.
- CC: two-digits representing the grid column
- RR: two-digits representing the grid row
- S: the side of the ballot, 1 for the front/recto, 2 for the back/verso
- P: the page of the ballot, 1 unless it is a multi-page ballot
Example: In the sample mark-sense ballot in Figure 4, in the contest for Justice of the Supreme Court, the first candidate is Hope S. Lost. The oval is in column 9 and row 10. It appears on side one of page one. The six-digit representation would be 091011.
All of the barcodes shown on the sample ExpressVote paper record (Figure 2) which are from the front page of the mark-sense ballot (ones where the fifth digit is a one) can be matched with the sample mark-sense ballot (Figure 4) using the grid in the same way.
The layout of ovals on the ballot grid is established during ballot design and will not be the same on all mark-sense ballots. The grid provides ballot design flexibility. For example, the front of the sample mark-sense ballot (Figure 4) has three columns at 01, 09, and 17, while the back (not shown) has two columns at 01 and 15.
Most candidates occupy two rows. Most write-in choices occupy three rows. In Figure 4, the candidate positions increment by two and the write-in choices increment by three.
The numbers encoded in the barcodes are similar because their location on the grid are similar. This is clear in the numbers representing the middle column on the sample ballot. The column, side, and page values are all the same, only the row number (in bold) changes.

091011 Hope S. Lost
092211 Don E. Brook
092411 Sue V. Neer
092611 Jack N. Abox
092811 Gloria S. Day

Write-Ins

ExpressVote ballot summary with a write-in vote for 'Joe' — Figure 5. Write-in coordinates

Write-in names are not stored in any barcode. If a voter chooses to write-in a candidate for a contest and enters a name into the ExpressVote, it will print a barcode containing a six-digit reference to the coordinates of the oval for the corresponding “Write-in” option on a mark-sense, pre-printed ballot. Using the sample mark-sense ballot with the grid overlay (Figure 4), in the contest for Justice of the Supreme Court, a write-in vote would encode 091411 in the barcode.
The write-in name appears in the ballot summary as “W/I:” followed by the name. An arrow on the far right of the paper record points at the name to draw attention to it.
One notable consequence of not storing write-in content in a barcode is that the ExpressVote is unable to scan the paper record and read the write-in content to a voter via the audio. It only says “Write in”.

Deconstructing an ES&S ExpressVote Paper Record

An explanation of how barcodes correspond to ballot selections.

General Structure

Encoded Data

Positions on a Mark-Sense Ballot Grid

Write-Ins

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