Packages shall preferably be loaded in open or ventilated vehicles or open or ventilated containers. If this is not feasible and packages are carried in other closed vehicles or containers, gas exchange between the load compartment and the driver's cab shall be prevented and the cargo doors of the vehicles or containers shall be marked with the following in letters not less than 25 mm high:

              "WARNING
           NO VENTILATION
         OPEN WITH CAUTION"

This shall be in a language considered appropriate by the consignor.

For UN Nos. 2211 and 3314 this mark is not required when the vehicle or container is already marked according to special provision 965 of the IMDG Code *).

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*) Warning mark including the words "CAUTION - MAY CONTAIN FLAMMABLE VAPOUR" with lettering not less than 25 mm high, affixed at each access point in a location where it will be easily seen by persons prior to opening or entering the vehicle or container.