18. An apparatus as defined in claim 15 , wherein the data unit encoder is to change the first text character in the source data to the second text character representative of the symbol by selectively replacing the first text character in the source data with the second text character.
18. An apparatus as defined in claim 15 , wherein the data unit encoder is to change the first text character in the source data to the second text character representative of the symbol by selectively replacing the first text character in the source data with the second text character. 19. An apparatus as defined in claim 18 , wherein the second text character representative of the symbol is substantially visually identical to the first text character in the source data.