Font switching can be prevented and the escape character output by doubling it (i.e. %%). Invalid codes (e.g. %51) will be output literally. The font switching character sequence does not have to be preceded or followed by blank characters. For example ‘ABC%04DEF%pGHI’ will be output as the 9-character string ‘ABCDEFGHI’ with the two sub-strings ‘ABC’ and ‘GHI’ in the principal font, and the middle three characters (i.e. ‘DEF’) in variation 4 (i.e. upright bold) of the principal font.