To exempt light diffusers and lenses from the requirements of Sentence 9.10.17.1.(1), which would otherwise limit surface flame-spread rating to 150, and permit a higher maximum flame-spread rating and require certain other conditions to be met as stated in Sentence 3.1.13.4.(1), on the basis that these building elements will not contribute significantly to the spread of flame.
To expand the application of Sentence 3.1.13.4.(1) to Part 9 buildings.