To modify the application of Sentence 9.23.15.2.(1), 9.23.16.2.(1), 9.27.8.1.(1), 9.27.9.1.(1), 9.27.10.1.(1), 9.29.7.1.(1), 9.29.9.1.(1) and 9.30.2.2.(1) so as to permit greater differences in nominal thicknesses than are permitted by the material standards, where expressly stated in Part 9.