# File lib_ctrl/rucy/params.rb, line 358
    def subprocess_group=(new_group)
      case (new_group)
      when Numeric
        if (new_group < 0) then
          raise "not allowed negative number of subprocess group: #{subprocess_group.inspect}"
        end
      when String
        # nothing to do.
      else
        raise "not allowed object type of subprocess group: #{new_group.class}"
      end
      @params['subprocess_group'] = new_group
    end