Relation pm#topic (?,pm#entity)
  supertype:  dc#Description  to specify an account of the content of a resource; in WebKB, pm#topic or pmdescr SHOULD BE USED INSTEAD
  subtype:  pm#annotation (?,pm#description_content/medium/container)
     subtype:  pm#descr (?,pm#description_content/medium/container)  for connecting an object to a formal representation of it, e.g., a representation written with a fcg
     subtype:  dc#Subject (pm#description,pm#entity)  to specify 1 or several topics; in WebKB, pm#descr SHOULD BE USED INSTEAD
     subtype:  pm#origin (?,pm#description_content/medium/container)
     subtype:  pm#use (?,pm#description_content/medium/container)
     subtype:  pm#advantage (?,pm#description_content/medium/container)
     subtype:  pm#disadvantage (?,pm#description_content/medium/container)
     subtype:  pm#definition (?,pm#description_content/medium/container)  see also #definition
        subtype:  rst#definition (pm#description_content/medium/container,pm#description_content/medium/container)  a logical relation should be used instead of this relation
     subtype:  pm#role (?,pm#description_content/medium/container)
     subtype:  pm#requirement (?,pm#description_content/medium/container)
     subtype:  pm#issue (?,pm#description_content/medium/container)
     subtype:  pm#trap (?,pm#description_content/medium/container)