What is the surface treatment of ct.ocd aluminum plate?

symbols for the features of plating layer and treatment features, Characteristic name compound

treatment method: Ep-- electroplating, Ap-- electroless plating, Et-- electrochemical treatment, Ct-- chemical treatment

treatment name: P-passivation, O-oxidation, A-anodization (including oxalic acid, sulfuric acid, chromic acid and phosphoric acid), Ec-- electrolytic coloring, etc.