DIAGNOSTIC VERB FORMS IN OLD RUSSIAN PAROEMIARIONS AND THE 13<sup>TH</sup>-CENTURY TOLSTOVSKY SBORNIK
The article examines variable verb forms whose distribution creates grammatical subsystems and determines the typology of texts. Such forms are diagnostic in nature. The article provides a complete list of diagnostic parameters based on the morphosyntax of the verb. The use of diagnostic forms such as the simple aorist, the aorist with an additional ending, imperfect with an additional ending, perfective imperfect, the perfect tense (third person), and some others, is described. The article analyzes handwritten material from the Paroemiarion connected to the Cyrillo-Methodian tradition and of varying origin. The status of the simple aorist in written Old Russian is clarified. The focus lies on the analysis of the variable forms of the verb in a megatext, the 13th-century Tolstovsky Sbornik, which includes both Old Russian originals and translated texts, as well as early lists of Bulgarian translated texts.