Intersection table representing the resolution of a many to many relationship.

high_rank_cls_s (FSK, M: CHAR VARYING(19))
lower_rank_cls_s (FSK, M: CHAR VARYING(19))

material_class.higher_ranking_class
Indicates various material classes which are ranked higher in value with respect to the property domain of the rank.
material_class.lower_ranking_class
Indicates various material classes which are ranked lower in value with respect to the property domain of rank.
high_rank_cls_s: Defines a foreign key to table material_class.
lower_rank_cls_s: Defines a foreign key to table material_class.