This error correcting, 2-dimensional matrix symbology was originally developed in 1989, and a finalized design was completed in 1995 by International Data Matrix. It's capable of encoding various character sets including strictly numeric data, alphanumeric data and all ISO 646 (ASCII) characters, as well as special character sets. The symbology has both error detection and error correction features. Each Data Matrix symbol consists of data regions , which contain nominally square or sometimes round cells set out in a regular pattern. All cells are the same size.  A dark cell  is a binary 1 and a light cell is a binary 0. Light cells on a dark background (negative) are possible but the reader must be set accordingly.
 There is no specified minimum or maximum for the X or Y dimension. The maximum capacity of the Data Matrix format is 144 X 144 rows. This is to say 3116 numeric characters or 2335 Alphanumeric  characters can be encoded into a single Data Matrix.
 The data region is surrounded by a finder pattern, a perimeter to the data region that is 1 cell wide, which is surrounded by a quiet zone on all four sides of the symbol. Two adjacent sides are solid dark lines used primarily to define physical size, orientation and symbol distortion. The two opposite sides consist of alternating dark and light cells. These are used primarily to define the matrix structure but also assist in determining physical size and distortion. 
There are 2 types of Data Matrix symbologies: *ECC 000 - 40 (Error Correction Code) with several available levels of convolutional error correction, and **ECC 200, which uses Reed-Solomon error correction. ECC 200 is recommended. The intellectual property rights associated with Data Matrix have been committed to the public domain.

*Obsolete
**New standard

ECC200 Data Matrix Encrypted Mark by TRUMPF LASER