The special jurisdictional rule in matters relating to a contract, laid down in Article 5(1) of the Convention of 27 September 1968 on Jurisdiction and the Enforcement of Judgments in Civil and Commercial Matters, as amended by the Convention of 9 October 1978 on the Accession of the Kingdom of Denmark, Ireland and the United Kingdom of Great Britain and Northern Ireland, is not applicable where, as in the present case, the place of performance of the obligation in question cannot be determined because it consists in an undertaking not to do something which is not subject to any geographical limit and is therefore characterised by a multiplicity of places for its performance. In such a case, jurisdiction can be determined only by application of the general criterion laid down in the first paragraph of Article 2 of that Convention.