About some sources for studying of Russian musical art reforming process in 17th

As a result of the activities of the masters-theorists, collected in Moscow under the orders of Tsar Alexei Mikhailovich in 1652 and 1669, the main musical and hymnographic material of chant handwritten books was revised and musical neumatic (znamenny) notation was improved. In the course of musical reform, in order to more accurately indicate the pitch, masters introduced unified cinnabar red ink signs in the form of letters of the alphabet and marks, written in black ink. The last ones were written in the form of strokes as constitutive parts of znamenny chant neuma. Both of these systems had the function of indicating musical pitch correlations between the neuma of znamenny notation. This is evidence that the musical theoreticians gradually passed from the neuma-formula thinking to the understanding that the melody consists of separate musical “degrees” (steps or sounds). All this brought together the Old Russian and European musical theories and allowed in the future to make a fairly rapid transition to the stylistically new Europeanized art in Russia. The author examines some of the written sources that give the opportunity for a more thorough study of the practical activities of the masters in preparing and conducting reform, the study of the theoretical principles of their editorial work.