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.
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. 4. The method according to claim 3 , wherein the dots along one and the same column (direction x) of the physical characters are of the same dimension, but possibly variable in the other dimension (y), and in that the distances between the columns may be any distance, including zero.