Gives the requirements for copolymers of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), conventionally described as fluoroethylene-propylene (FEP), as films, with or without surface treatment to render the surface cementable and heat sealable, for type 1: General purpose; for type 2A: One side treated; for type 2B: Two sides treated.