(2) The court may revoke all or part of a patent only on the grounds set out in Articles 138 (1) and 139 (2) EPC. Technically qualified judges must have a university degree and proven expertise in a field of technology. They must also have a proven knowledge of civil law and relevant procedures in patent litigation. 3. Subject to the agreement of the competent body, the parties may agree on the use of the language in which the patent was granted as the language of the proceedings. If the body does not approve its choice, the parties may request that the case be referred to the Central Chamber. .