1 . PRELIMINARY RULINGS - REFERENCE TO THE COURT - NECESSITY OF PRELIMINARY RULING - ASSESSMENT BY THE NATIONAL COURT ( EEC TREATY , ART . 177 ) 2 . COMMON CUSTOMS TARIFF - TARIFF HEADINGS - HEADINGS 26.02 AND 31.03 - SUBHEADINGS 31.03 A II AND 31.03 B - SCOPE - CRITERIA - CLASSIFICATION OF CONVERTER SLAG