| 摘要 |
The envelope (19) comprises a rectangular sheet of material including two right-angled triangles with a hypotenuse (11) having a join tongue (7) along one side and also intersecting one of the sheet corners. The sections of the sheet joined to the rectangular part are folded about the join line to overlap with the tongue above the rectangular part, and the sheet is joined to itself along the tongue and along its catheter edges. |
