four different versions (sizes) of Micro QR codes: the smallest is 11×11 modules; the largest can hold 35 numeric characters. IQR code IQR Code is an alternative to existing QR codes developed by Denso Wave. IQR codes can be created in square or rectangular formations; this is intended for situations where a rectangular barcode would otherwise be more appropriate, such as cylindrical objects. IQR codes can fit the same amount of information in 30% less space. There are 61 versions of square IQR codes, and 15 versions of rectangular codes. For squares, the minimum size is 9 × 9 modules; rectangles have a minimum of 19 × 5 modules. IQR codes add error correction level S, which allows for 50% error correction. IQR Codes have not yet been given an ISO/IEC specification, and only proprietary Denso Wave products can create or read IQR codes. Secure QR code Secure Quick Response (SQR) code is a QR code that contains a "private data" segment after the terminator instead of the specified filler bytes "ec 11". This private data segment must be deciphered with an encryption key. This can be used to store private information and to manage company's internal information. SQR codes have been developed by the FORUS Foundation to enable secure transactions, and published under a Creative Commons Licence. The SQR solution guarantees the integrity of the source data as well as the validity of the originating party. The payment instruction string is made up of the electronic instruction data from the scanned QR code appended with a SHA-2 cryptographic hash. The message digest can then be encrypted using the private key of the sender, which then creates a digital signature of the message. This signature validates the integrity of the data and the trustworthiness of the sender. This provides non-repudiation, confirming the identity of the sender, and that it has not been tampered with during transmission. By embedding the URL and all the variables required to perform shopping cart type e-commerce, bill payment and peer to peer payments, coupled with a digital certificate eliminates the possibility of spoofing, tampering, and man in the middle attacks. Frame QR Frame QR is a QR code with a "canvas area" that can be flexibly used. In the center of this code is the canvas area, where graphics, letters, and more can be flexibly arranged, making it possible to lay out the code without