The Aztec Code 1995 Allyn developed by Andy Longacre at Welch in the USA. He is a free 2D Code with the U.S. Patent No. 5591956th It is scaled according to ISO / IEC 24778. The name Aztec Code is derived from the high culture of the Aztecs in Central Mexico and their step pyramids: When looking at a step pyramid from the sky, then it is very similar to the recognizable directly in the code - center squares, which are centered around a single point.
The focus of the code is the search element, which consists of several nested squares. The symbol elements are also square. It can currently small (from 12 characters) to large amounts of data (currently more than 3,000 characters) are encoded. The contents can be divided into several symbols. The Reed -Solomon error correction supports up to 32 user-specific security levels. The reconstruction of the data content is possible even when up to 25% (for small codes up to 40% even ) of the code have been destroyed. In contrast to all other codes no rest zones are required. The code may be placed at any position.
A precise code specification is included in the patent.
Currently, the German railway, the Austrian Federal Railways Czech Railways, Trenitalia, the Wiener Linien, the Swiss Federal Railways, the Association of German Transport Companies and the Association of Train Operating Companies, this encoding method to use for their online tickets. Even with most airlines it is in use.