# Conceptual Product Structure

## How to Assign Final Items and Rules to a Neutral Item

| ### What to do:
| Select Start > Bill of Materials > Neutral Item The Neutral Item mask is opened.
| Search for ART-13.
| Select the Final Items tab.
| To change to insert mode click .
| Click in the Item Number field. The Items list is opened.
| Select ART-13_1 Pen Cap Blue from the Items list.
| To save the entry click .
| Repeat steps 4 to 7 and select the following items:
Item Number | Name
ART-13_2 | Pen Cap Red
ART-13_3 | Pen Cap Silver
| Select ART-13_1 and to change to edit mode click .
| Enter ; in the Rule short field.
| To save the entry click .
| Repeat steps 9 to 11 and enter the following data:
Item Number | Name
ART-13_2 | +Rubber;
ART-13_3 | +Rubber/+rubber;
| When entering the rule for a final item, you need to ensure that the specifications are available in the scope of the modular BOM, where the neutral item is used. The system does check if the rule is syntactically correct (i.e.boolen expression with operators like '+', '-', '/', etc.). It does not check if the entered specifications are available (simply because at this stage it is not finally determined in which modular BOMs the neutral item will be used). If the specifications you entered are not available in the scope of a specific modular BOM, the system will generate a runtime error.