5. The method according to claim 3 , wherein the characters with a definition greater than 2 columns are composed of a non-limitative succession of columns of any length and composition, the last preferably comprising at least the mixed dot (½ white dot+½ black dot).
3. The method according to claim 1 , wherein the physical structures include one or more so-called control/extension columns and a value column, while the computing structures include as many bytes as there are columns, wherein the physical structures defined by 2 columns at least one is value and at least one is control/extension, these structures comprising: 2 dots reserved for the extension of the coding of the value coded by the value column, 1 dot characterising the parity of the number of its own black dots, 1 dot for the parity of the number of black dots in the value column, 1 dot specifying the parity of the number of segments formed from black dots in the value column, 1 dot giving the state of the first dot in the value column, 1 dot indicating whether the present column is the last of the character or whether the following control/extension column also forms part of it, and the value column being formed by dots generally weighted to a power of 2 increasing from 2 0 as from the header.