The designation in accordance with the UNE 21-123 standard will consist of two letters that respectively indicate the composition of the insulation and the cover, a hyphen followed by a third letter F that indicates the flexible formation and the word "SUMERGED PUMPS". D = Ethylene propylene insulation R = Cross-linked polyethylene insulation N = Polychloroprene cover or similar with SE 1 characteristics Example: 2-conductor cable with ethylene propylene insulation and a section of 2.5 mm2, the designation would be: DN - F 0, 6/1 kV Submerged pumps 2x2.5 mm2