The resurrected sticheras of the Octoechos were originally set to music in the material of the Old Sticherarium.
They later split off, functioning as an independent and self-contained musical code. He was joined by members of the Papadiki and the eothinas serving the liturgical needs of the Vespers and Orthros services.
In many of these codes the usual Protheory of Psalter was proposed[...]
(From the preface of the publication)
