- Standard TB/T 3237 Flame retardant technical specification of decorating materials for multiple unit train Test Method GB 2406 Oxygen index test UIC 564 Combustion test GB 8323 Smoke density test TB 3237 Part 4.4 Smoke toxicity test Reference Standard GB/T 2406.2 Plastics - Determination of Burning Behavior by Oxygen Index GB/T 10707 Rubber - Determination of the Burning GB/T 8323.2 Determination of Optical Density by a Single-chamber Test UIC 564-2 Regulations relating to fire protection