25In that connection, it must be stated that, as regards the conditions for the validity of a jurisdiction clause, Article 23(1) of the Regulation sets out in substance the formal requirements and mentions only one substantive condition relating to the subject-matter of the clause which must concern a particular legal relationship. Therefore, the wording of that provision does not indicate whether a jurisdiction clause may be transmitted, beyond the circle of the parties to a contract, to a third party, a party to a subsequent contract and successor, in whole or in part, to the rights and obligations of one of the parties to the initial contract.