Postal envelope with internal information copying layer

摘要

The envelope is formed by a single folded sheet (1) defining at least one rear panel (3) and a single front panel (4). One of the faces of either the front or rear panels includes a layer of material (2) for transferring impressions made on it onto another sheet contained within the envelope. The impression transfer layer may correspond to the area (6) of the envelope on which postal franking is to be made. The transfer layer is typically formed of transferable colouring or marking material, e.g. carbon copy paper.