Linear or one-dimensional (1D) bar codes are limited in the amount of data that can be encoded. This limitation led to the development of a two-dimensional (2D) symbology composed of rows of data arranged in a rectangular or square pattern. The rows of data are stacked onto each other to encode an array of data.
One example of a a two-dimensional (2D) bar code symbology is Data Matrix (also known as datamatrix). As you can see in the sample image at the right, the Data Matrix symbol consists of light and dark square data modules representing zeroes or ones. In addition, a Data Matrix has an L-shaped border called the “finder pattern” which is used to locate and orient the symbol. The other two borders consist of alternating dark and light cells called the “timing pattern” which provides a count of the number of rows and columns. Within the borders are rows and columns of cells of encoded data. As more data is encoded in the symbol, the number of rows and columns will increase ranging from from 8×8 to 144×144. Data Matrix can encode up to 2,335 alphanumeric characters and has built-in error checking and correction algorithms that enable reconstruction of encoded data when the symbol is damaged. By the way, the above sample contains the text “Get mobile with DecisionPoint”.
The most popular application for Data Matrix is marking small items. Data Matrix is used for the Item Unique Identification (IUID) asset identification system instituted by the United States Department of Defense (DoD) because it can encode item details such as manufacturer ID, serial number and part number.