Within the size & type code, consisting of 4 numerals, the last 2 specifies the types in the following manner. : The first digit indicates the category of the container. [ 0= General Purpose | 1= Closed, ventilated | 2= Dry bulk non pressurised box type | 3 = refrigerated / heated | 4 = insulated, reefer, heated with removable equipment | 5 = open top | 6 = platform| 7= tank| 8= Dry bulk non pressurised hopper type | 9 = air containers. Now the second digit specifies the precise type within the above broad categories.