Product_class

e	Class_category_association
e	Class_condition_association
e	Class_inclusion_association
e	Class_specification_association
d	Expression_operator
d	Id_for_class
e	Product_class
e	Product_class_relationship
e	Specification
e	Specification_category
e	Specification_category_hierarchy
e	Specification_expression
d	Specification_for_category
e	Specification_inclusion
d	Specification_operand_select