Manuscripts with notation in the restored Bulgarian state, after Byzantine rule from 1018 to 1187, continued the tradition from former times of being written in Slavic (old-Bulgarian) and Greek, a bilingual practice that was established during the time of SS. Cyril and Methodios. The Greek language did not have an ethnic connotation: it was perceived as the language of the rich culture of Antiquity and as a liturgical language. Most of the manuscripts originated from the south-western Bulgarian lands. Those in Slavic belong to the type of Menaia and Triodia-Pentekostaria; fewer of them are Oktoechoi. The Menaion, the Triodion-Pentekostarion, and the Oktoechos all together constitute the book of the Sticherarion. The manuscripts in Slavic were notated in the Palaeo-Byzantine notation of the archaic adiastematic type. The musical signs in them could be characterized as "instructions" for singing: they did not fix the exact pitch of the tone but only gave the direction of the melody. The manuscripts in Palaeo-Byzantine notation can be systematized into three groups: manuscripts that were partly notated in the Palaeo-Byzantine notation of the Coislin and/or the Chartres type, manuscripts in theta notation, and manuscripts that were fully notated in Palaeo-Byzantine notation. In the Bulgarian libraries from the period under consideration, there are also preserved manuscripts in Greek. They are of the Sticherarion type and were notated in Middle Byzantine notation. The origins of these Sticheraria are linked to the Bachkovo monastery. Manuscripts in Slavic notated in Middle Byzantine notation have not been found and there is no evidence that this notation was adapted to the Slavic language — either in Bulgaria, or in any other Slavic Orthodox country. However, it does not mean that this notation was not known in any one of them: the Middle Byzantine manuscripts in Greek preserved in the Bulgarian libraries prove that this notation was known. As a whole, till the end of the 13th century, the manuscripts with notation offer a picture of a very dynamic musical practice. Various types of notation show the various levels to which church music developed and functioned: all of the notated manuscripts display a high professional level; the partly notated manuscripts and these in theta notation — indicate an oral level with particular characteristics.
Greek notated manuscripts, Middle Byzantine notation, Palaeo-Byzantine notation, Slavic notated manuscripts, Studite Typikon, Гръцкоечните нотирани ръкописи, Славяноезничните нотирани ръкописи, средновизантийска нотация, старовизантийска нотация, Студийския устав
