illustrated, it is the most comprehensive reference work for these Australian issues. Most stamped envelopes are collected as entires. In the 19th century the practice was to collect cut squares (or cut-outs in the U.K.) which involved cutting the embossed indicia from a postal envelope. This destroyed the envelope. As a result, one cannot tell from a cut square what specific envelope it came from and, many times, the cancellation information. The manner in which the stamped envelope is cut before folding (that is, its knife) vanishes on a cut square. The envelope size disappears, too, with a cut square. In collecting entires, a single indicium may appear on many different sizes of envelopes. Some countries have issued the same indicium on different paper types: laid and wove. Likewise it is common for the same indicium to be embossed onto paper of several different colors. Finally, two envelopes of the same size can have a different flap size indicating that they were cut from a different knife. Rarely, an uncatalogued color, or displaced surcharge, or albino indicium, or inside-out folding of the envelope may appear, in which case you have found something of value. All of these attributes relate to mint or unused envelopes. When you add a postmark from a used envelope to the mix, the collecting possibilities explode. What was formerly in fashion, collecting only mint examples, has changed because many collectors seem to find used PSE collections more interesting. Some postal stationery envelopes contain a corner card, a printed return address on the envelope, usually in the upper left hand corner. This can range from a simple town and country notation to an elaborate illustrated advertisement for a business. Corner cards are either applied by an after-market print shop or by dealing with the government related entity that produces the stamped envelopes. See also Illustrated stamped envelope References Further reading Higgins & Gage World Postal Stationery Catalog, 19 volumes covering the whole world. Out of print, but worth looking for. Huggins, A.K.; British Postal Stationery, A Priced Handbook of the Postal Stationery of Great Britain, Great Britain Philatelic Society, 1970 Thorp-Bartels Catalogue of U.S. Stamped Envelopes, Century Edition, 1954 Cutting Knife Handbook by United Postal Stationery Society, 1999. Envelope knives illustrated. External links Cuban Postal Envelopes, 1899 - 1949. Philatelic terminology Postal stationery