| 摘要 |
A roofing material includes a sheet of flexible material having two parallel long sides and two short end edges joining the long sides. The material has pre-printed thereon a plurality of longitudinal guide lines extending parallel to the long sides of the material. The guide lines are equally spaced and arranged in a repeating sequence across the width of the material to form identical groups of a plurality of guide lines. Each guide line of a group is visually distinct from the others in the group. The material further includes a plurality of different indicator markings, one indictor marking corresponding to each group of guide lines to enable each group of guide lines to be distinguished from the other groups.
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