GBK is also the IANA-registered internet name for the Microsoft mapping,[1] which differs from other implementations primarily by the single-byte euro sign at 0x80.

GB abbreviates Guójiā Biāozhǔn, which means national standard in Chinese, while K stands for Extension (扩展 kuòzhǎn).

[3] However, all major web browsers decode GB2312-marked documents as if they were marked GBK, except for Safari and Edge on the label GB_2312.

[5] In 1993, the Unicode 1.1 standard was released, including 20,902 characters used in mainland China, Taiwan, Japan and Korea.

While GBK included all the Chinese characters defined in Unicode 1.1 and GB 13000.1-93, these standards used different code tables.

The newly added 95 characters were not found in GB 13000.1-1993, and were provisionally assigned Unicode PUA code points.

[1] W3C's technical recommendation published in 2015[9] defines a GBK encoder as a GB 18030 encoder with a single-byte euro sign and without four-byte sequences (while W3C's GBK decoder specification has no such limitation, decodes as GB 18030, i.e. with same range of letters as all of Unicode).

More specifically, the following ranges of bytes are defined: In graphical form, the following figure shows the space of all 64K possible 2-byte codes.

Green and yellow areas are assigned GBK codepoints, red are for user-defined characters.

GB 2312, or more properly the EUC-CN encoding thereof, takes a pair of bytes from the range A1–FE, like any 94² ISO-2022 character set loaded into GR.