1 . PROCEDURE - FORMS OF ACTION PROVIDED BY THE EEC TREATY AGAINST AN INSTITUTION ' S REFUSAL TO PAY - ACTION FOR PAYMENT - INADMISSIBILITY - REMEDY AT LAW OF PERSONS CONCERNED - ACTION FOR A DECLARATION OF NULLITY OR FOR FAILURE TO ACT - CONDITIONS ( EEC TREATY , ARTS 164 , 173 , 175 AND 176 ) 2 . ACTION FOR A DECLARATION OF NULLITY - ACTS WHICH MAY BE THE SUBJECT OF AN ACTION - REFUSAL TO PAY - ACT DEFINING UNEQUIVOCALLY AND DEFINITIVELY THE INSTITUTION ' S POSITION ( EEC TREATY , ART . 173 ) 3 . SOCIAL POLICY - EUROPEAN SOCIAL FUND - ADMINISTRATION AND CONTROL - POWERS OF THE COMMISSION - SCOPE - DETERMINATION OF TIME-LIMITS FOR CLEARANCE OF FUND ' S ACCOUNTS - FAILURE TO OBSERVE - PENALTIES - PERMISSIBILITY ( EEC TREATY , ART . 124 ; REGULATION NO 2396/71 OF THE COUNCIL , ARTS 11 AND 13 ) 4 . COMMUNITY LAW - PRINCIPLES - LEGAL CERTAINTY - PRECLUSIVE PERIODS - WHEN APPLICABLE - CONDITIONS - CLEAR AND PRECISE DETERMINATION - DECISION 78/706 , ART . 4 ( 1 ) - CONDITIONS UNFULFILLED ( COMMISSION DECISION 78/706 , ART . 4 ( 1 ))