| 摘要 |
The invention relates to the use of a security feature which can be verified by rubbing together two parts of the sheet and security documents made therefrom. A sheet 10 has at least two areas 11,12 displaced laterally from each other, said areas being provided with surface relief in the form of a plurality of embossed lines raised relative to the normal plane of the sheet. The sheet is foldable to enable the at least two areas to be brought into contact with each other and rubbed relative to each other thereby giving rise to an audible sound and a distinct tactile effect. |
