Common and Supporting
services
To provide comprehensive support and proper exchange of evidence between Data Services and Online Procedure Portals, the Once-Only Technical System uses Once-Only common services and additional supporting services.
![illustration Once Only Technical System (OOTS)](https://ec.europa.eu/digital-building-blocks/sites/download/attachments/615481586/illu-introduction.png)
Common services
The Commission provides Common Services to help the Member States ensure the proper exchange of evidences.
Data Service Directory
The Data Service Directory is a common service that acts as a catalogue of evidence types that can be provided upon request.
Evidence Broker
The Evidence Broker is an authoritative system that maps specific data sets as evidence types that prove specific requirements.
Semantic Repository
The Semantic Repository is a common service that acts as a data portal for the technical system.
Supporting services
Testing service
The OOTS Testing service assists national teams in implementing the Once-Only Technical System. Information on available testing services, including the test platform and other tools to facilitate testing are available on a restricted wiki space.
If required, please request access to the restricted wiki via the Service Desk.
If you have questions contact the service desk on EC-OOTS-SUPPORT@ec.europa.eu
Service desk
The Service Desk helps users improve the performance, continuity and reliability of their Once-Only Technical System implementations.