def parent_key
      groups = self.c000.split('-').reverse!
      changed = false
      groups.map! do |group|
        if changed || group == "00000"
          group
        else
          changed = true
          "00000"
        end
      end
      c000 = groups.reverse!.join('-')
    end
def parent_key
      groups = self.c000.split('-').reverse!
      changed = false
      groups.map! do |group|
        if changed || group == "00000"
          group
        else
          changed = true
          "00000"
        end
      end
      c000 = groups.reverse!.join('-')
    end
--- Instance Methods ---