.Basic Table Calculation.
      TC cmd is ,for ex.,used to calculate elapsed time from timestamp
      data,summarize elapsed time then output average elapsed time.
      Operation +,-,*,/,% is available between 2 table columns.
      Summary supports subtotal by key-break or line-count.
      By column format function,data column is alligned by space delimiter,
      it enable to process data,for ex.,vmstat output(unix cmd).
      See next section for sample usage.