The article deals with the types of constructive conditionality of syntactic units, compares different approaches to the problem of the relation between the linguistic unit and the context. Constructive conditionality is understood as the result of interaction of form (structure), semantics and syntactic function. Conditional syntaxes are those whose semantics depends on their syntactic function. Unlike syntactic case marking of syntactic functions independently of the semantics of the noun and the semantics of the sentences, due to syntaxeme implement its semantics in the composition of models with a certain standard value. The form of the indirect case is interpreted not as a dependency marker, but as a means of organizing the obligatory component of the predicative syntactic construction. The article discusses the substantive syntaxeme “do+Genus. p.” modal-event (do shutok / ne do shutok; do razgovorov / ne do razgovorov: ne do sna), modal-deliberative (ne do lyudej, ne do knig, ne do iskusstva), modal-evaluative (ne do vezhlivosti, ne do gordosti, ne do spravedlivosti) values and syntactic constructions, the components of which are syntaxes “do+Genus.p.” Offers a comparative analysis of similar structure and semantics of the sentences, identifies the semantic features indicate the relationship of the semantics of syntaxeme with the level of the sentence: modality, negation, presence/ absence of the control, mono/polysubject, the degree of categorical statements.