This standard was previously known as KS C 5601. There have been several revisions of this standard. For example, there were revisions in 1987, 1992, 1998 and 2002. Several computer operating systems encode various versions of this standard several ways. Not all of them encode the standard the same way, like replacing the typical backslash at byte 0x5C with the won currency sign (₩). Some operating systems extend this standard in other non-uniform ways. Possible encoding schemes of KS X 1001 are: EUC-KR, windows-949 (superset of EUC-KR)[clarification needed], ISO-2022-KR and JOHAB. However, the latter two encodings are rarely used.