NFC Forum Type 3 compatible Tag, card, or token, including a contactless IC chip, which has built-in memory and memory access functions. The physical shape is not defined. The basic unit of information used in memory management is called a block. Each block has a fixed size of 16 bytes. The number of memory blocks available depends on the chip hardware. Memory blocks are not addressed directly but relative to the Service they belong to. Services are similar to files in a file system. Each Service has a number of memory blocks associated with it. Services can be addressed using their Service Code, which must be unique inside each Type 3 Tag. Each Type 3 Tag contains management data, called system Information. The System Information of a Type 3 Tag consists of the following parts: