In order to foster handwriting discipline, a type of ruling known as Seyès ruling  is used on paper in schools. Heavy horizontal lines are printed 8 mm (appx. 5/16 in) apart, with three lighter lines 2 mm (appx. 5/64 in) apart between each pair of heavy lines. Heavy vertical lines are spaced 8 mm (appx. 5/16 in) apart, beginning 16 mm (appx. 5/8 in) from the left-hand edge of the page.  These sheets of paper are generally known as grands carreaux (large tiles) as opposed to the petits carreaux (small tiles) which are 5x5mm. Seyès ruled paper is available in single sheets ( copies simples ) or joined double sheets ( copies doubles ) which are sometimes preferred for exams, being easier to handle.