Sybase 12.4.2 manual Multibyte character sets, 321

CHAPTER 9 International Languages and Character Sets

Multibyte character sets

	Some languages, such as Japanese and Chinese, have many more than 256
	characters. These characters cannot all be represented using a single byte, but
	can be represented in multibyte character sets. In addition, some character sets
	use the much larger number of characters available in a multibyte
	representation to represent characters from many languages in a single, more
	comprehensive, character set.
	Multibyte character sets are of two types. Some are variable width, in which
	some characters are single-byte characters, others are double-byte, and so on.
	Other sets are fixed width, in which all characters in the set have the same
	number of bytes. Adaptive Server IQ supports only variable-width character
	sets.
Example	As an example, characters in the Shift-JIS character set are of either one or two
	bytes in length. If the value of the first byte is in the range of hexadecimal
	values from \x81 to \x9F or from \xE0 to \xEF (decimal values 129-159 or 224-
	239) the character is a two-byte character and the subsequent byte (called a
	follow byte) completes the character. If the first byte is outside this range, the
	character is a single-byte character and the next byte is the first byte of the
	following character.
	•	The properties of any Shift-JIS character can be read from its first byte
		also. Characters with a first byte in the range \x09 to \x0D, or \x20, are
		space characters.
	•	Characters in the ranges \x41 to \x5A, \x61 to \x7A, \x81 to \x9F or \xA1
		to \xEF are considered to be alphabetic (letters).
	•	Characters in the range \x30 to \x39 are digits.
	In building custom collations, you can specify which ranges of values for the

first byte signify single- and double-byte (or more) characters, and which specify space, alpha, and digit characters. However, all first bytes of value less than 64 (hex 40) must be single-byte characters, and no follow bytes may have values less than 64. This restriction is satisfied by all known current encodings.

For information on the multibyte character sets, see “Using multibyte collations” on page 336.

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