Relation pm#domain_related_relation__domain-related-thing (?,?)
  supertype:  relation_playing_a_special_role  this type permits to categorize relations according to their roles ; this is a traditional but quite subjective way of categorizing relations
  instance of:  virtual_relation_type
  subtype:  relation_from_a_domain__thing_in_domain (domain,?)
     subtype:  subdomain__true-subdomain (domain,domain)  in WebKB-2, ">part" is an abbreviation of this relation since it is not  
 a part relation nor a specialization relation but a mix of both; 
 for details, see http://www.webkb.org/kb/it/o_domain/d_field_of_study.html
     subtype:  domain_object (domain,?)
        subtype:  core_domain_object__central_object_of_domain (domain,?)
  subtype:  relation_from_a_thing_that_is_not_a_domain__thing_in_domain_of_object (thing_that_is_not_a_domain,?)
     subtype:  object_subdomain__subdomain_of_object (thing_that_is_not_a_domain,domain)
     subtype:  object_in_domain_of_object (thing_that_is_not_a_domain,thing_that_is_not_a_domain)  all relations non exclusive with this one are subtypes of this one; this is stated via:
 pm#relation subtype: {(pm#object_in_domain_of_object  pm#relation_from_a_domain pm#object_subdomain)};
  subtype:  relation_to_a_domain__sub-domain_or_object-subdomain (?,domain)
     subtype:  subdomain__true-subdomain (domain,domain)  in WebKB-2, ">part" is an abbreviation of this relation since it is not  
 a part relation nor a specialization relation but a mix of both; 
 for details, see http://www.webkb.org/kb/it/o_domain/d_field_of_study.html
     subtype:  subdomain_of_object (?,domain)
  subtype:  relation_to_a_thing_that_is_not_a_domain__domain-related-object (?,thing_that_is_not_a_domain)
     subtype:  domain_object (domain,?)
     subtype:  object_in_domain (?,thing_that_is_not_a_domain)