System takes both of department code(2 digits) and item code(6 digits) to find at ITMGNL.ITMITMCD , then system retives item code where item code digit = ITMGNL.ITMITMCD(1,8)
Example :
Department Code = 10
Item Code = 001011
System retives item code where item code digit = ITMGNL.ITMITMCD(1,8)
Result: Item Code = 10001011001
Item Code = 10001011002
System takes Item code to find Item ID at ITMGNL table because Item by Site table always keeps Item ID.