 During the 9th through 11th centuries a number of systems were developed to specify pitch more precisely, including diastematic neumes whose height on the page corresponded with their absolute pitch level (Longobardian and Beneventan manuscripts from Italy show this technique around AD 1000).Digraphic notation, using letter names similar to modern note names in conjunction with the neumes, made a brief appearance in a few manuscripts, but a number of manuscripts used one or more horizontal lines to indicate particular pitches.The treatise "Musica enchiriadis" (AD 900) uses Daseian notation for indicating specific pitches, but the modern use of staff lines is attributed to Guido d'Arezzo (AD 990–1050), whose four-line staff is still used (though without the red and yellow coloring he recommended) in Gregorian chant publications today.