More detailed information about the specifications and the specification documents are available on the Finnish-language page.
Interfaces and instructions for connecting to the national code service
The document ”Kansallisen koodistopalvelun rajapinnat ja liittymisohje” (Interfaces and instructions for connecting to the national code service) describes the basic principles of connecting to the national code service, the tasks upon connecting to, and the support of the service in testing and problem situations.