1. Definitions and examples. Writing polycondensates 1.1 Official IUPAC definitions and other designations The general reactions (1) and (2) describe both polycondensations and polyadditions: (n+1)A—X—A+(n+1)B—Y—B→A—[X—A′B′—Y—B′A′]n—X—A′B′—Y—B+C