Here are the valid ranges of bytes according to its encoding structure.
|Byte Range Purpose||Byte Range in Hexadecimal||Comment|
|single byte||41-F9||Includes graphic characters. Does not include unassigned characters nor ISO control characters.|
|full width space|| 40 40
|shift to single byte mode||0A 41|
|shift to double byte mode||0A 42|
|first byte of double byte||40, 41-FE|| A1-CF is the basic set. D0-FE is extended set 1. 59-80 is extended set 2. 81-A0 are user defined characters.|
Byte 40 is only valid when followed by byte 40.
|second byte of double byte||40, 41-FE||40 is only valid when preceded by byte 40. 0x40 0x40 makes the ideographic space character. Normally only A1-FE is used.|
- Lunde, Ken. CJKV Information Processing. Sebastopol, Calif.: O'Reilly & Associates, 1998. ISBN 1-56592-224-7. (Note that Appendix D has a typo for the hexadecimal ranges for KEIS. The decimal ranges were used for the encoding structure.)