Supply input values for an unconnected Lookup transformation from a :LKP expression in another transformation. The arguments are local input ports that match the Lookup transformation input ports used in the lookup condition. Use the following syntax for a :LKP expression:
argument, argument, ...
To continue the example about the retail store, when you write the update strategy expression, the order of ports in the expression must match the order in the lookup condition. In this case, the ITEM_ID condition is the first lookup condition, and therefore, it is the first argument in the update strategy expression.