To the question of the early period Old Russian phonological system description

The article attempts to present the early period Old Russian phonological system. The main attention is paid to the characteristics of the vocalism subsystem in the 6th – 9th centuries. The review is conducted from the standpoint of the phonological units' classification of different levels proposed by B.I. Osipov; phonemes proper, syntagm-phonemes and paradigm-phonemes that combine the ideas of different phonological schools and directions. The possibilities of combining vowel phonemes, as well as the nature of their opposition, are described and the question of their phonological status is solved.