def write
      node = to_rxf_node(@members.root , 0)
      io = StringIO.new
      node.out( io , 0 )
      io.string
    end
def write
      node = to_rxf_node(@members.root , 0)
      io = StringIO.new
      node.out( io , 0 )
      io.string
    end
Initialized with the Members (hash of occurences, see there)
 main function, creates nodes from the occurences and writes the nodes to a string
 returns the rxf formatted string for all objects