| 摘要 |
FIELD: postal service. SUBSTANCE: letter envelope has row of inclined notches in compliance with adhesive layer on opposite side on which closing flap is to be bonded. At end of row of inclined notches there is a special large notch of other inclination. This notch is used for beginning the opening of envelope by breaking notches located in line when respective end flap is tightened up. Second special notch is used for detection of attempt of unauthorized opening of envelope. In pulling the second end of flap (in trying to separate it from opposite side of envelope), envelope will be broken in transversal direction. EFFECT: enhanced reliability. 14 cl, 13 dwg
|
