The aim of the edition is to present the composer's enormous legacy as it is known today, as exhaustively as possible. Every musical text published in this edition is an outcome of the comprehensive analysis of extant sources realized by the scientific editor of the respective volume. According to several sources, P. I. Tchaikovsky himself was aware that the changes and amendments, he entered into his scores, would be of great importance for his works' future performers. The present project's important scientific objectives include the fixation and thoroughly verified reproduction of all the changes made by the composer, so that the scholars and musicians of today could perceive and realize the author's creative ideas in all their entirety.