CONVENTION OF 27 SEPTEMBER 1968 ON JURISDICTION AND THE ENFORCEMENT OF JUDGMENTS IN CIVIL AND COMMERCIAL MATTERS - PROROGATION OF JURISDICTION - WRITTEN AGREEMENT CONTAINING A JURISDICTION CLAUSE AND STIPULATING THAT THE AGREEMENT CAN BE RENEWED ONLY IN WRITING - EXPIRY OF THE AGREEMENT - MAINTENANCE OF BUSINESS RELATIONS BETWEEN THE PARTIES - VALIDITY OF THE JURISDICTION CLAUSE - CONDITIONS ( CONVENTION OF 27 SEPTEMBER 1968 , ART . 17 )