“VistA is a health information system deployed across all veteran care sites in the United States. VistA provides clinical, administrative, and financial functions.”
The system and the front-end GUI are provided as open-source software. The VA has created a version that runs on GT.M on Linux, said to be to meet the needs of private healthcare organizations. It is in use in non-VA healthcare facilities around the U.S. (Whether these extra-VA uses are incidental or intentional to the VA’s development efforts is unclear.) Its use globally is promoted and contributed to via WorldVistA. It is unclear whether WorldVistA is a membership organization.