pm#quintary_relation_type  relates five items
  exclusion:  pm#binary_relation_type  pm#ternary_relation_type  pm#quaternary_relation_type  pm#variable_arity_relation_type
  supertype:  pm#relation_type  there are three kinds of relation(_types): pm#predicate_type, pm#function_type and sumo#list; both predicates and functions denote sets of ordered n-tuples; the difference between these two classes is that predicates cover formula-forming operators, while functions cover term-forming operators; a list, on the other hand, is a particular ordered n-tuple
  instance of:  pm#class_of_inheritable_relation_type
  equal:  sumo#quintary_relation (pm)
  subtype:  pm#quintary_predicate_type  class of predicates that require five arguments
  subtype:  pm#quaternary_function_type  class of functions requiring four arguments

No statement uses or specializes pm#quintary_relation_type; click here to add one.