# File lib/logging/layouts/parseable.rb, line 195
    def items=( ary )
      @items = Array(ary).map {|name| name.to_s.downcase}
      valid = DIRECTIVE_TABLE.keys
      @items.each do |name|
        raise ArgumentError, "unknown item - #{name.inspect}" unless valid.include? name
      end
      create_format_method
    end