This code implies that all low-slope roof covering materials must be able to withstand typical impact loads, such as foot traffic, hail and driving rainstorms.
The American Architectural Manufacturers Association recently released an updated document using ASTM test methods to qualify windows, doors and skylights as "impact resistant."
Roof coverings installed on low-slope roofs (roof slope <2:12) in accordance with Section 1507 shall resist impact damage based on the results of tests conducted in accordance with ASTM D 3746.