+/// Third entity for the constraint
+const std::string CONSTRAINT_ATTR_ENTITY_C("ConstraintEntityC");
+/// Fourth entity for the constraint
+const std::string CONSTRAINT_ATTR_ENTITY_D("ConstraintEntityD");
+/// List of constraint attributes
+const unsigned int CONSTRAINT_ATTR_SIZE = 4;
+const std::string CONSTRAINT_ATTRIBUTES[CONSTRAINT_ATTR_SIZE] =
+ {CONSTRAINT_ATTR_ENTITY_A, CONSTRAINT_ATTR_ENTITY_B,
+ CONSTRAINT_ATTR_ENTITY_C, CONSTRAINT_ATTR_ENTITY_D};