GBK is an extension of the GB 2312 character set for Simplified Chinese characters, used in the People's Republic of China. It includes all unified CJK characters found in GB 13000.1-93, i.e. ISO/IEC 10646:1993, or Unicode 1.1. Since its initial release in 1993, GBK has been extended by Microsoft in Code page 936/1386, which was then extended into . GBK is also the IANA-registered internet name for the Microsoft mapping, which differs from other implementations primarily by the single-byte euro sign at 0x80.