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Hangul OpenType Specification | Terms | Shaping | Features | Other | Appendix


Features for the Korean Hangul script

The features listed below have been defined to create the basic forms for the languages that are supported on Korean Hangul systems. Regardless of the model an application chooses for supporting layout of complex scripts, Uniscribe requires a fixed order for executing features within a run of text to consistently obtain the proper basic form. This is achieved by calling features one-by-one in the standard order listed below.

The order of the lookups within each feature is also very important. For more information on lookups and defining features in OpenType fonts, see Encoding feature information in the OpenType font development section.

The standard order for applying Korean Hangul features encoded in OpenType fonts:

Feature Feature function Layout operation Required
Language based forms:
ccmp Character composition/decomposition substitution GSUB
ljmo Leading consonant Jamo GSUB X
vjmo Vowel Jamo GSUB X
tjmo Trailing consonant Jamo GSUB X
       
[GSUB = glyph substitution, GPOS = glyph positioning]



Character composition (and decomposition)

Feature Tag: "ccmp"

The 'ccmp' feature is used to compose a number of glyphs into one glyph (GSUB lookup type 4). This feature is implemented before any other features because there may be times when a font vender wants to control certain shaping of glyphs.

This feature permits the composition of Old Hangul Jamos corresponding to sequences described in Appendix B. To compose Old Hangul syllables, these Jamo glyphs are then substituted to the appropriate form using the 'ljmo', 'vjmo' and 'tjmo' features. The 'ccmp' feature should be implemented before any other feature, so that these actions are given topmost priority. It is applicable to each of: Leading, Vowel and Trailing Jamo sequences.

For Example: the below sequence (U1107 + U1109 + U1110) of leading Jamos composed with the 'ccmp' feature.


Leading consonant Jamo

Feature Tag: "ljmo"

The 'ljmo' feature is used to substitute the correct shape of a leading consonant Jamo for a Hangul syllable. The shaping of leading consonant Jamos is context based and depends on whether the leading Jamo is followed by a vowel Jamo alone or a sequence of vowel and trailing Jamo.

For Example: the leading Jamo (U1113) is replaced by the correct leading form when followed by a vowel Jamo alone.


Vowel Jamo

Feature Tag: "vjmo"

The 'vjmo' feature is used to substitute the correct shape of a vowel Jamo for a Hangul syllable. The shaping of vowel Jamos is context based and depends on whether it is preceded by a leading Jamo alone, or a leading Jamo and followed by a trailing Jamo.

For Example: the Hangul vowel Jungseong AE (U1162) is replaced by the correct form when preceded by a leading Jamo alone.


Trailing consonant Jamo

Feature Tag: "tjmo"

The 'tjmo' feature is used to substitute the correct shape of a trailing consonant Jamo for a Hangul syllable. The shaping of trailing consonant Jamos is context based and depends on whether the trailing Jamo is preceded by a leading Jamo filler and vowel Jamo or by a leading Jamo and vowel Jamo.

For Example: U11C7 is replaced by the correct trailing consonant when preceded by a leading Jamo and vowel Jamo.


More Examples:

1. Old Hangul Jamo containing leading consonants, vowels and trailing Jamos.

Input sequence: This sequence consists of: Choseong Pieup, Choseong Sios, Choseong Thieuth, Jungseong O, Jungseong Ya, Jungseong I, Jongseong Rieul, Jongseong Mieum, Jongseong Hieuh.

'ccmp' feature applied:

'ljmo', 'vjmo' and 'tjmo' features applied:

2. Leading consonant Jamo + vowel Jamo + trailing Jamo.

Input sequence: This sequence consists of: Choseong Ssangkiyeok, Jungseong A, Jongseong Nieun-Sios.

'ljmo', 'vjmo' and 'tjmo' features applied:

3. Leading consonant Jamo + vowel Jamo

Input sequence: This sequence consists of: Choseong Nieun-Kiyeok, Jungseong Ae.

'ljmo' and 'vjmo' features applied:



this page was last updated 7 April 2003
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Hangul OpenType Specification | Terms | Shaping | Features | Other | Appendix
Microsoft Typography | Developer information | Specifications | OpenType font development