This model is adequate to describe all parts of speech for contemporary standard Russian.
A zero ending in Russian is considered to be an ending. The importance of zeros in Russian grammar is evident not only from the nominative case of masculine or
third declension nouns, but also in the formation of the genitive plural (cf. стол (nom. sg. 1st decl. masc.), церковь (nom. sg. 3rd decl. fem.), книг (gen. pl. 2nd decl.), окон (gen. pl. 1st decl.)). Verbal forms also have zero endings in some imperative forms (for example, the second person singular imperative of –aj verbs (читай, сделай, работай) and some –i verbs (звони, ходи, лови)).