An identification key always starts with a company prefix. There are company prefixes of different lengths: from 7 digits to 11 digits long. The prefix is supplemented with an x number of digits to arrive at a complete identification key (for example, GTIN). The shorter the company prefix, the more free positions to identify products with. In other words, the shorter the company prefix, the more identification numbers you can create. We call this the 'numbering capacity'. The last digit is a check digit to verify that the code is correct.