Packages shall preferably be loaded in open or ventilated wagons or open or ventilated containers. If this is not feasible and packages are carried in other closed wagons or containers, gas exchange between the load compartment and accessible compartments during carriage shall be prevented and the cargo doors of the wagons 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 wagon or container is already marked according to special provision 965 of the IMDG Code 1).

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1) 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 cargo transport unit.