The "Once only" principle is a concept aimed at reducing the administrative burden and improving the efficiency of public administration
The Once-Only Technical System connects EU public authorities, so they can exchange official documents and data at the citizen’s request. It puts into practice the Once-Only Principle, which states that citizens should not be forced to provide information to authorities if another authority already holds that information in electronic format.
| 01 | Interoperability level | Technical interoperability |
| 02 | Interoperability sublevel | Data presentation and exchange Distributed Application Architecture Interconnection Services Web Services Data integration and middleware File type and document formats XML-based standards Message transport and security File and message transfer protocols |
| 03 | Interoperability type | - |
| 04 | Institution | CENTRAL STATE OFFICE FOR DEVELOPMENT OF DIGITAL SOCIETY |
| 05 | Language | ENGL |
| 06 | Country | - |
| 07 | Authors of the document | - |
| 08 | Restrictions on use | - |
| 09 | Compliance with EU funds | - |