Relation pm#relation_to_a_domain__sub-domain_or_object-subdomain (?,domain)
  closed_exclusion:  relation_to_a_thing_that_is_not_a_domain
  supertype:  domain_related_relation__domain-related-thing
  instance of:  virtual_relation_type
  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)