Relation pm#owner (?,causal_entity)  this is not a function: 0..N owner allowed
  exclusion:  attributive_relation  purpose  has-author  owned-by  owner_of  leader  seller  customer  generator  creator  spatial_origin  exploits  has_purpose  has_purpose_for_agent  measure  attribute  name  Date  value  rdf_reification_relation  support  example  syntax  has-magnitude
  supertype:  attributive_relation  who_relation
  inverse:  owner_of
  subtype:  sole_owner (? -> causal_entity)