Bettaccini TITJUR Opinion of Mr Advocate General Jacobs delivered on 14 April 1994. Lio Bettaccini v Fonds National de Retraite des Ouvriers Mineurs. Reference for a preliminary ruling: Tribunal du travail de Mons - Belgium. Social security for migrant workers - Increase in invalidity pension - Application of national rules against overlapping of benefits. Case C-301/93.