In 1984 Chris Hakkennes (1916-2003) has published his Graduale Lagal. The word Lagal is a contraction of Laon and Saint Gall; two places referring to the earliest (tenth-century) surviving mass proper manuscripts with Gregorian chant in musical notation. These manuscripts, however, were adiastematic, i.e. precise intervals could not be read. Instead all kinds of information for performance practice is much better readable than in later sources. For the so called semiological performance practice this information is of crucial importance.
For his Graduale Lagal Hakkennes developed a new, proportional notation, in which this information is displayed in a selfevident way. The tenth-century manuscripts at issue are the same as those copied in Graduale Triplex (1979) and Graduale Novum (2011). In all cases the pitches were taken from eleventh and twelth century manuscripts. Hakkennes was far ahead of his time, both in his notation and his reconstruction. Unfortunately his work has been neglected so far.
After 1984 several updates of his Graduale Lagal appeared with new melodic corrections. Below you find the first editions in pdf. The original first edition was published in one volume by Stichting Centrum voor de Kerkzang in 1984. The Ordinarium was not included in this edition. Later editions were published in eight parts in a box by Stichting Lagal in Utrecht. The division in parts is followed below, however, the first seven parts were scanned from the original 1984 edition, only part 8 is from 1990.
C.F.J. Hakkennes, Graduale Lagal (The Hague 1984):
Part 1 - Tempus Adventus & Nativitatis Domini
Part 3 - Tempus Paschale
Part 4 - Tempus per annum 1
Part 5 - Tempus per annum 2
Part 7 - Diversa (wedding, funeral, gloria ... index)