&1 &2 requires a reference to a class

What causes this issue?

You have tried to create the iPPE object &v1& &v2& without assigning it
to a product class. The Customizing for type &v1& requires such an
assignment.

System Response

The system does not allow you to create the iPPE object if you haven't
defined a product class. The Customizing for this node type states that
it must be assigned to a product class.

How to fix this error?

Assign the iPPE object &v1& &v2& to a product class by maintaining the
fields for the class type and class number.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.