In these and other works Ockeghem's compositional choices seem game-like, especially to singers reading from the original mensural notation.    From Wordnik.com.  [Archive 2009-05-01] Reference

This peculiarity and the fact that these mixed forms employ both mensural and modal notation in alternation pose problems for the performer which can only be solved, as Higinio Anglès pointed out, by subjective musical sensibility.    From Wordnik.com.  [Archive 2009-07-01] Reference

At the same time new techniques of composition evolved and were refined: the various sections of Mass settings were unified by means of a constantly recurring cantus firmus and by identical biginnings to the movements, while increasingly complex canonic techniques were developed, and the number of voices and sections, the mensural succession and even compositional techniques were established for certain types of motets.    From Wordnik.com.  [Archive 2009-06-01] Reference

Two types of notation are employed: Franconian or modal notation, characteristic of the Ars Antiqua, used in the Kyrie, Sanctus and Agnus Dei, and a mensural notation, showing the clerk’s mastery of the innovations brought in with the Ars Nova in the Gloria, Credo and Ite missa est.    From Wordnik.com.  [Archive 2009-04-01] Reference