Stateful Encodings

Stateful encoding uses sequences of control codes, such as shift-in/shift-out, to change character sets associated with specific code values.

For instance, under compound text, the control sequence "ESC$(B" can be used to indicate the start of Japanese 16-bit data in a data stream of characters, and "ESC(B" can be used to indicate the end of this double-byte character data and the start of 8-bit ASCII data. Under this stateful encoding, the bit value 0x43 could not be interpreted without knowing the shift state. The EBCDIC Asian code sets use shift-in/shift-out controls to swap between double- and single-byte encodings, respectively.

Converters that are written to do the conversion of stateful encodings to other code sets tend to be a little complex due to the extra processing needed.