ISO 657-13:1981

Hot-rolled steel sections — Part 13: Tolerances on sloping flange beam, column and channel sections

Specifies a) tolerances for the thickness of the web and the flanges along with a higher mass tolerance given in table 8, column 3 (symbol D for dimensional tolerance), or b) where no tolerances are specified for the thickness of the web and the flanges, tighter mass tolerances given in a table 8, column 2, are applicable (symbol M for mass tolerance).