++++ Community law - Principles - Equal treatment - Discrimination on grounds of nationality - University studies in a Member State preparing for a qualification for an occupation - Enrolment fee or "minerval" payable only by nationals of other Member States - Refusal by universities to enrol nationals of other Member States who cannot be taken into account for the purposes of the universities' financing - Restriction of the possibilities for nationals of other Member States to obtain reimbursement of "minervals" unduly paid - Prohibition (EEC Treaty, Arts 5 and 7)