The principal aim of the witness test is to check the long term behaviour (several decades) of the EBS and the host rock in conditions representative of the planned ones. It will also give the opportunity to test long term monitoring devices. Furthermore the witness test will be an "engineered analogon" for future generations. The Witness test could be installed after dismantling and interpretation of the previously mentioned in-situ test (except the heater test which could be continued for a large time span). The installation of the witness test is not planned before 2017.