Relation dc#Description (?,entity)  to specify an account of the content of a resource; in WebKB, pm#topic or pmdescr SHOULD BE USED INSTEAD
  exclusion:  Type
  supertype:  binary_relation (pm)  in WebKB, most relation types are binary and some have a variable number of arguments (as in KIF), hence this type is currently only specialized by types that I do not want to see as direct subtypes of pm#relation
  subtype:  topic (?,entity)
     subtype:  annotation (?,description_content/medium/container)
        subtype:  descr (?,description_content/medium/container)  for connecting an object to a formal representation of it, e.g., a representation written with a fcg
        subtype:  Subject (description,entity)  to specify 1 or several topics; in WebKB, pm#descr SHOULD BE USED INSTEAD
        subtype:  origin (?,description_content/medium/container)
        subtype:  use (?,description_content/medium/container)
        subtype:  advantage (?,description_content/medium/container)
        subtype:  disadvantage (?,description_content/medium/container)
        subtype:  definition (?,description_content/medium/container)  see also #definition
           subtype:  definition (description_content/medium/container,description_content/medium/container)  a logical relation should be used instead of this relation
        subtype:  role (?,description_content/medium/container)
        subtype:  requirement (?,description_content/medium/container)
        subtype:  issue (?,description_content/medium/container)
        subtype:  trap (?,description_content/medium/container)
  subtype:  url (?,URL)
  subtype:  file_or_file_element (?,description_container)
     subtype:  file (?,document_element)
        subtype:  home_page (?,document_element)
     subtype:  file_element (?,document_element)
     subtype:  descr_in__descrin (?,description_container)  when a thing t has a description stored in a description container dc, there is a relation pm#descr_in from t to dc
        subtype:  descr_container__description_support___descr_support (description,description_container)  permits to associate a statement with an object on which it is represented
  subtype:  version_info__versioninfo (? -> entity)  generally, a string giving information about this version; e.g., RCS/CVS keywords
  subtype:  title (? -> string)  for connecting an object to its "title" in a natural language
  subtype:  comment  for connecting an object to an informal representation of it, typically a node with a string inside; in WebKB, the FT and FCG notations permit to avoid using this relation type