Deviating from the provisions of the ADR/RID/ADN, the subsidiary hazard of Class 3 is not indicated in the Dangerous Goods List in Table 3-1 of the ICAO TI for this UN No. An enquiry at the PTB about the flash point revealed that mixtures containing HCN definitely develop flammable vapours. However, measurements are needed to assess the extent. Substances that emit highly toxic gases and vapours in addition to flammable ones cannot be measured for their flash point by the PTB. Because of the lack of information on the flash point, the consideration of the BMDV to submit an application to the UN (TDG) for the insertion of the Class 3 subsidiary hazard was postponed for the time being.