A character (or set of characters) that uniquely defines the specific use of the data or the general category of the data field encoded in the bar code symbol following it. Data Matrix Data Matrix from CiMatrix is a 2-D matrix code designed to pack a lot of information in a very small space. A Data Matrix symbol can store between one and 500 characters. The symbol is also scalable between a 1-mil square to a 14-inch square. That means that a Data Matrix symbol has a maximum theoretical density of 500 million characters to the inch! The practical density will, of course, be limited by the resolution of the printing and reading technology used.