# Conceptual Product Structure

## How to Create Specification Constraints

| ### What to do:
| To work through this example, you must first complete the examples Create Specification Categories, Create Specification and Assign Specifications to Product Variants and set up a cooperation partner. Alias ID
| Select Start > Bill of Materials > Specification. The Specification mask is opened.
| Search for Ornamental Ring with the specification Rubber. The product variant BP Junior should be assigned to this specification.
| Select the Constraints tab.
| To change to insert mode click .
| The field Restriction is automatically filled with the standard value ;.
| Enter +rubber; in the Constraint field and select the Inclusion check box.
| Specification Contraints must not contain the following special characters: <> '" ^ &
| To save the entry click .
| This example defines, when using the product variant BP Junior with a rubber ornamental ring, a rubber press button has to be included to the product.
| The entries in the Constraint field depend on the specification names. Logical operators have to be added to define the inclusion or exclusion.