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It has to be checked if it is possible to store this tokem to Audit Repository. If not then a new repository has to be introduces. Although as Massi said it is proposed to be inside the Audit Repository.
As a first implementation they will be stored in filesystem 

The tokens are stored under %EPSOS_PROPS_PATH%/obligation/nrr and %EPSOS_PROPS_PATH%/obligation/nro and the filename includes the submission timestamp, the creation timestamp, the event type and the uuid of the message

Release Planning

The project that will be changed to achieve this functionality is https://bitbucket.org/openncp/protocol-terminators

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