GBKs

GBK, often referred to collectively as GBKs, is a character encoding standard used for Simplified Chinese, an extension of the earlier GB2312 standard. It was designed to accommodate thousands of additional characters and symbols beyond GB2312. It is also known as Guobiao Kuozhan, meaning national standard extension.

GBK is a mixed single-byte and double-byte encoding. ASCII characters (0x00–0x7F) are encoded as single bytes, while Chinese characters are represented with two-byte sequences. The first byte of a double-byte character falls in the range 0x81–0xFE and the second in 0x40–0xFE, excluding 0x7F. It is a superset of GB2312 and can represent far more characters.

GBKs have been widely used in Windows, other Chinese operating systems, and many legacy systems, often implemented as code page 936 (CP936). They maintain compatibility with GB2312 for shared characters, but GBK adds many more. Data encoded in GBKs may not round-trip cleanly with UTF-8 without conversion.

GBKs are not defined as an ISO/IEC standard; they function as a national extension in China. In the 2000s, China introduced GB 18030, a newer mandatory standard that supersedes GBK and GB2312 and is fully Unicode-compatible. In practice, GBKs remain in use for legacy data and systems, even as GB18030 and Unicode become more prevalent.

See also: GB2312, GB18030, Unicode, code page 936.