A Waffeleinpressung case of stamps is a security measure against repeated use of the trademark. In these stamps a waffle -like pattern or grid was (English: BBQ ) by a Gaufrage imprinted, which should include the stamp color better. In this case the fibers of the paper have been breached, the color was better able to penetrate and punch the washing of the paint was difficult there. This protective measure, there was the case of stamps from the United States in the 1860s and 1870s, and soon after in Peru.
The lattice types of the United States have been divided according to the chronological appearance alphabetically by William L. Stevenson. Even before that there were approaches to classify them, but the system of Stevenson has since become the standard. Stevenson himself had assembled a reference collection, which came as a donation of a few intermediate owner of the New York Public Library.
The best-known type is the Z Grill. This type recognized Stevenson later, so he is not in the alphabetical order. The oldest type is the A grill, with the entire stamp surface. After the A grill was found the brands but too badly damaged, were minted so soon instead of the total area, only some smaller rectangles.