| 摘要 |
The one plate (5) is coloured red and is intended to mark the left side of the film (3), whilst the other (6) is coloured green to mark the right side of the film (3). Marking is by shade-forming material, pref. lead, which is moulded into the plate material. The marking combination is seen as a picture turned the right way round, with weak print from the flat side receiving the radiation. |
