The HKSCS has gone through a few iterations.
Big-5 extensions (1995–2009) HKSCS versions up to HKSCS-2008 are encoded in
Big5 (Big5-HKSCS, big5hk) and
ISO 10646 (
Unicode).
GCCS Due to the inherent differences between
standard written Chinese and
written Cantonese, the Government of Hong Kong recognised the need for a standardised set of
proprietary characters that would allow for the streamlining of electronic communication; at the time, the
Big5 Chinese encoding scheme did not contain a vast majority of these characters (some were erroneously cross-listed with similar characters). The Government Chinese Character Set () or GCCS was thus developed by the government, providing an additional 3,049 hanzi supplementing the 13,053 present in Big5. The character set consists of Chinese characters commonly used in Hong Kong. Some characters are
Cantonese-specific, while some are alternative forms of characters. The set is not well-organised and the characters are not closely examined. Additionally, Hong Kong's Department of Judiciary made use of an additional extension on top of the base GCCS set, adding a further 145 characters. These were included in the and rows of Big5. Of these, 84 were removed as a result of unification with Big5 characters or with other HKSCS characters. The other 22 GCCS characters removed in HKSCS-1999 were retired as "not verifiable". where they are sourced from Adobe-CNS1-1, an
Adobe-CNS1 supplement implemented to support GCCS.
HKSCS-2001 and HKSCS-2004 Following the acceptance of HKSCS-1999, newer revisions were released in 2001 (adding 116 new characters) and in 2004 (adding 123 new characters), totalling 4,941 characters. However, to preserve compatibility with programs that generated PUA code points, the already-allocated code points are reserved, and no new characters will be mapped to the private use area.
HKSCS-2008 Since around 2005, many Hong Kong and
Macau websites have switched encoding from Big5-HKSCS to Unicode, including
HKGolden. The last edition of HKSCS to encode all of its characters in Big5 was HKSCS-2008,
Unicode subsets (2015 onwards) HKSCS-2016 By 2015, efforts were underway in Hong Kong to migrate away from Big5-HKSCS and towards a defined subset of Unicode, at the time tentatively termed the
Hong Kong Character Set (HKCS). This was planned to be published by the end of 2015 as "HKCS-2015", and to have four parts differentiated by different
Unihan source prefixes: • Source prefix followed by Big5
hexadecimal:
character repertoire of HKSCS-2008 in the narrow sense • Source prefix followed by Big5 hexadecimal: character repertoire of Big5-ETEN • Source prefix followed by a four-digit decimal incremental
accession number: post-2008 vertical extensions (i.e. newly submitted
CJK Unified Ideographs) • Source prefix followed by hexadecimal Unicode code point: post-2008 horizontal extensions (i.e. the addition of a Hong Kong reference glyph and source reference to an existing CJK Unified Ideograph) In particular, 22 horizontal extensions were already planned for inclusion as of June 2015. These were all minor
variants of existing Big5 characters containing the 昷/𥁕, 兑/兌 and 吿/告 components, for which Hong Kong font conventions were closer to those of
mainland China than to those of
Taiwan, but for which the preferred versions had been encoded separately from the Big5 versions in the
Unified Repertoire and Ordering due to the source separation rule. Of these 22 characters, 14 were considered "core" characters for Hong Kong use. Ultimately, HKSCS-2016 added a total of 24 characters relative to HKSCS-2008, 22 of which were the source-separated variants of existing Big5 characters. As such, the characters added in HKSCS-2016 are referenced to Unicode only, and were not added to the Big5 extension.
Amendments to HKSCS-2016 , four additional characters have been approved by the Chinese Language Interface Advisory Committee (CLIAC) for inclusion in HKSCS as amendments following the publication of HKSCS-2016: in January 2019, and in February 2021, and in February 2025.
Macao Supplementary Character Set Similarly to Hong Kong's situation, there are also characters that are needed by
Macau but included in neither Big5 nor HKSCS, hence, the
Macao Supplementary Character Set was developed, building on HKSCS with additional Unicode-mapped characters. The first batch of 121 MSCS characters were submitted for addition to or horizontal extension in Unicode (as appropriate) in 2009. At the time, the term
Macao Information Systems Character Set (
MISCS) was in use for the entire character set, while "MSCS" referred more narrowly to the additional characters only. • Source prefix followed by Big5 hexadecimal: character repertoire of HKSCS-2008 in the narrow sense (same as ) • Source prefix followed by level number and Big5 hexadecimal: character repertoire of Big5-ETEN (same as ) • Source prefix followed by a five-digit decimal incremental accession number: Macau-specific vertical extensions. This prefix had initially been in 2009, but was shortened to for vertical extensions in 2020, while horizontal extensions had their source references replaced with references. • Source prefix followed by hexadecimal Unicode code point: Macau-specific horizontal extensions • Source prefix followed by hexadecimal Unicode code point: horizontal extensions from HKSCS-2016 (same as ) • Source prefix followed by hexadecimal Unicode code point and a three-digit decimal number: used for variation sequences registered in the
Ideographic Variation Database (IVD) == Compatibility ==