This part of EN ISO 7792 establishes a system of designation for thermoplastic polyester (TP) material, which may be used as the basis for specifications. It covers polyester homopolymers for moulding and extrusion based on poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(cyclohexylenedimethylene terephthalate) (PCT), poly(ethylene naphthalate) (PEN) and other TP-types and copolyesters of various compositions for moulding and extrusion.