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Interoperability is the extent to which systems from different manufacturers and devices with different system configurations can communicate with each other. Past election equipment generally used proprietary data formats, thus a device from one manufacturer would not "talk" directly to another device from another manufacturer. To transmit voter data from, say, a database to a manufacturer’s election management system, software might have to be written to reformat the data from the database into the manufacturer’s format. Building the software may be complex and difficult. This can have the effect of "locking" states and localities into using the same configuration of manufacturer equipment they have invested in, because it's too much trouble and expense to move to something newer or more desirable and appropriate. A common data format changes all of this and leads to greater interoperability among devices and manufacturers.

Common Data Formats for Voting Systems

NIST has developed common data formats (CDF) for election data to make voting data and ultimately voting equipment interoperable. The development work is conducted within public working groups, formed as needed and composed of election officials, manufacturers, election analysts, and the public. The Election Assistance Commission (EAC) Voluntary Voting System Guidelines (VVSG) requires that EAC-certified voting systems be capable of using the CDFs for data imports and exports where applicable.  The VIP (Voting Information Project) format, supported by Google, is consistent with the NIST CDFs in naming and usage of data items for pre- and post-election data and results.

What is an election data CDF?

Election equipment deals primarily with election data - data about candidates, contests, ballots, and results. A voting system is made up of many different devices, including databases, electronic pollbooks for checking voters into the polls, touch screen devices for electronic voting, optical scanners for scanning marked ballots, and election management systems used for tabulation of votes. A CDF is simply a format that, for a particular use case, can be used when importing and exporting election data among the various election equipment so that the export/imports are uniform and interoperable across different voting system manufacturers. The common data formats use XML, the eXtensible Markup Language, and JSON, the JavaScript Object Notation, which can be more space efficient than XML. An example of using XML is as follows, with the data encoded with XML tags that each describe the data, e.g.,


            <ContestName>2024 Presidential, State of West Virginia</ContestName>


                        <CandidateName>John J. Jones</CandidateName>




For additional overview information, see an Introduction to the CDF project.

CDF and related specifications

There are currently four CDF specifications completed, each located in its own GitHub repository.  

  1. NIST 1500-102 Cast Vote Records – for cast vote records created when scanning ballots, used to determine election results -
  2. NIST 1500-101 Election Event Logging – for election-related events logged by election devices for use in auditing -
  3. NIST 1500-100 Election Results Reporting – for defining election information and for reporting election results -
  4. NIST 1500-103 Voter Records Interchange – for voter registration-related records to support voter registration and for voter registration database exchanges -

CDF development also makes use of the following specifications:

  1. Election Business Process Modeling – for defining and modeling election processes for the purposes of informing use case development for CDF projects and showing where interoperability between processes may be beneficial and worthwhile to pursue -
  2. Glossary of Election Terms – consistent with the EAC VVSG 2.0 glossary, developed to ensure that the CDF formats are uniform in their naming and use of election data -

For more information, please contact Lisa Carnahan.

Created July 21, 2017, Updated November 29, 2021