Wansung Code has the drawback that it only assigns codes for the 2350 precomposed Hangul syllables which have their own KS X 1001 (KS C 5601) codepoints (out of 11172 in total, not counting those using obsolete jamo), and requires others to use eight-byte composition sequences, which are not supported by some partial implementations of the standard.

[1] Unified Hangul Code is not registered with IANA as a standard to communicate information over the Internet.

However, the W3C/WHATWG Encoding Standard used by HTML5 incorporates the Unified Hangul Code extensions into its definition of "EUC-KR".

[10] The WHATWG treat the label "ks_c_5601-1987" interchangeably with "EUC-KR" with the intent of being "compatible with deployed content".

[16][17][18][19][20] It differs in having a single byte mapping of 0x5C to the Won sign (U+20A9);[21][22][23] Windows maps 0x5C to U+005C (the Unicode code point for the backslash) as in ASCII,[14] although fonts often still render it as a Won sign.