This Element recognizes a categoryless functional element in syntax and unifies the syntax of coordination and modification.

In a coordination construction, which is universally available, two or more syntactic constituents are combined, with or without an overt coordinator. This Element examines how coordinate structures are derived syntactically, focussing on the syntactic operations involved, including constraints on both their operations and the representations they produce. Specifically, considering the recent research development in the syntax of coordination, the Element discusses whether any special syntactic operation is required to derive various coordinate constructions, including constructions in which each conjunct has a gap, whether there is any special functional category heading coordinate constructions in general, what the morphosyntactic statuses of coordinators (i.e., conjunctions and disjunctions) are in some specific languages, whether the structure of a coordinate construction can be beyond the binary complementation structure, and whether the mobility of conjuncts and the mobility of elements in conjuncts require any construction-specific constraint on syntactic operations.