The definition of SBS modified bitumen roofing is influenced by several key process parameters. These include the type and concentration of SBS (styrene-butadiene-styrene) polymer used, the mixing temperature, and the shear rate during the blending process. Additionally, the duration of mixing and the cooling rate after modification play crucial roles in achieving the desired properties, such as elasticity, adhesion, and resistance to aging. Proper control of these parameters ensures optimal performance of the modified bitumen.