#open_chain  a chain of atoms in a molecule whose ends are not joined to form a ring
  exclusion:  #closed_chain
  supertype:  #chemical_chain__chain  a series of linked atoms (generally in an organic molecule)
  subtype:  #branched_chain  an open chain of atoms with one or more side chains attached to it
  subtype:  #straight_chain  an open chain of atoms with no side chains

No statement uses or specializes #open_chain; click here to add one.