1 . CONVENTION ON JURISDICTION AND THE ENFORCEMENT OF JUDGMENTS - PROROGATION OF JURISDICTION - APPEARANCE OF THE DEFENDANT BEFORE THE COURT SEISED - AGREEMENT CONFERRING JURISDICTION DESIGNATING ANOTHER COURT - EFFECT ( CONVENTION OF 27 SEPTEMBER 1968 , ARTS 17 AND 18 ) 2 . CONVENTION ON JURISDICTION AND THE ENFORCEMENT OF JUDGMENTS - PROROGATION OF JURISDICTION - APPEARANCE OF THE DEFENDANT BEFORE THE COURT SEISED - CHALLENGE AS TO JURISDICTION AND DEFENCE ON THE SUBSTANCE - APPEARANCE NOT CONFERRING JURISDICTION - CONDITIONS ( CONVENTION OF 27 SEPTEMBER 1968 , ART . 18 ) 3 . CONVENTION ON JURISDICTION AND THE ENFORCEMENT OF JUDGMENTS - PROROGATION OF JURISDICTION - AGREEMENTS CONFERRING JURISDICTION - FORMAL REQUIREMENTS - RULES OF THE CONVENTION - STIPULATION BY A CONTRACTING STATE OF OTHER REQUIREMENTS - NOT PERMISSIBLE - APPLICATION TO PROVISIONS ON LANGUAGES ( CONVENTION OF 27 SEPTEMBER 1968 , ART . 17 )