Field help (ITMREF4) 

It is the product reference for which a document line is recorded. It is possible to:

The entry of the product is used to initialize the Description and Sales unit fields, which can be modified. The sales unit can be modified on the condition that it is chosen from the suggested list that contains the sales and packing units from the product and product-customer records.

At this stage, a warning message can appear that to inform the user of the replacement of the entered product by the substitute product. This automatic substitution only takes place when the following two conditions are fulfilled:

SEEWARNING Once the lie is populated, the product code can no longer be modified. The line has to be deleted and recreated to modify the code.