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Typographic features made possible using digital typographic systems have solved many of the demands placed on computer systems to replicate traditional typography and have expanded the possibilities with many new features. Three systems are in common use: OpenType , devised by Microsoft and Adobe , Apple 's Apple Advanced Typography (AAT), and SIL 's Graphite . The lists below provide information about OpenType and AAT features. Graphite does not have a fixed set of features; instead it provides a way for computer fonts to define their own features.
OpenType typographic features [ edit ] The OpenType format defines a number of typographic features that a particular font may support. Some software, such as Adobe InDesign , LibreOffice /OpenOffice , or recent versions of Lua /XeTeX , gives users control of these features, for example to enable fancy stylistic capital letters (swash caps) or to choose between ranging (full-height) and non-ranging (old-style, or lower-case) digits. Some web browsers also support OpenType features in accordance with the CSS Fonts Module Level 3 specification, which allows OpenType features to be set directly via the font-feature-settings
The following tables list the features defined in version 1.8.1 of the OpenType specification. The codes in the "type" column are explained after the tables.
OpenType features may be applicable only to certain language scripts or specific languages, or in certain writing modes. The features are split into several tables accordingly.
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Long name tag type Description
Above-base Forms abvfS1
Replaces the above-base part of a vowel sign. For Khmer and similar scripts.
Above-base Mark Positioning abvmP4,5
Positions a mark glyph above a base glyph.
Above-base Substitutions abvsS4
Ligates a consonant with an above-mark.
Below-base Forms blwfS4
Replaces halant+consonant combination with a subscript form.
Below-base Mark Positioning blwmP4,5
Positions a mark glyph below a base glyph
Below-base Substitutions blwsS4
Ligates a consonant with a below-mark.
Pre-base Forms prefS4[ disputed – discuss ]
Replaces halant+consonant at the end of a consonant cluster with a glyph at the beginning. Khmer, Myanmar, Malayalam, Telugu
Pre-base Substitutions presS4,5
Ligates consonant combinations.
Post-base Substitutions pstsS4
Ligates a final consonant+consonant.
Post-base Forms pstfS4
Replaces final halant+consonant with special form. Khmer and Gurmukhi, Malayalam
Distance distP2
Adjusts horizontal positioning between glyphs. (Always enabled, as opposed to 'kern'.)
Akhand akhnS4
Hindi for unbreakable . Ligates consonant+halant+consonant, usually only for k-ss and j-ny combinations.
Halant Forms halnS4
Replaces a glyph for final consonant+halant .
Half Form halfS4
Replaces consonant+halant with a half form, indicating it is part of a conjunct.
Nukta Forms nuktS4
Replace consonant+nukta (dot mark) with single glyph.
Rakar Forms rkrfS4
Replaces halant+ra with a rakar glyph, indicating it is part of a conjunct.
Reph Form rphfS4
Replaces initial ra+halant with a final reph mark, indicating part of a conjunct.
Vattu Variants vatuS4
Replaces consonant+rakar combinations with a vattu variant ligature.
Conjunct Forms cjctS4
Ligates consonant+halant+consonant, indicates part of a conjunct.
Conjunct Form After Ro cfarS1
Khmer
[ edit ]
Long name tag type Description
Simplified Forms smplS1
Replaces sinograms with their simplified versions, may be language dependent
Traditional Forms tradS1,3
Replaces Chinese characters with their traditional versions
Traditional Name Forms tnamS1
Japanese alternates for proper names
Expert Forms exptS1
Typographic alternatives for some Japanese tetragrams
Hojo Kanji Forms hojoHojo alternates for Japanese tetragrams
NLC Kanji Forms nlckNLC alternates for Japanese tetragrams
JIS 78 Forms jp78S1,3
JIS C 6226-1978 alternates for Japanese tetragrams, not accessible per Unicode
JIS 83 Forms jp83S1
JIS X 0208-1983 alternates for Japanese tetragrams, not accessible per Unicode
JIS 90 Forms jp90S1
JIS X 0208-1990 alternates for Japanese tetragrams, not accessible per Unicode
JIS 04 Forms jp04JIS 2004 alternates for Japanese tetragrams, not accessible per Unicode
Hangul hnglS1,3
Transliterates Chinese-style characters with Korean Hangul
Leading Jamo Forms ljmoS4
Initial group of consonants for a synthesized Korean Hangul tetragram
Trailing Jamo Forms tjmoS4
Final group of consonants for a synthesized Korean Hangul tetragram
Vowel Jamo Forms vjmoS4
Medial group of vowels for a synthesized Korean Hangul tetragram
Full Widths fwidS1
Replaces proportionally spaced character with full-width versions (esp. for Latin letters within Chinese)
Half Widths hwidS1, P1
Replaces uniformly-spaced characters with half-width version
Alternate Half Widths haltP1
Re-positions full-width glyphs on half-width spaces
Third Widths twidS1, P1
Replaces uniformly-spaced character with a version of 1/3 width (punctuation, etc.)
Quarter Widths qwidS1
Replaces uniformly-spaced glyphs with quarter-width ones (punctuation etc.)
Proportional Widths pwidS1
Replaces uniformly-spaced glyphs with proportional ones
Proportional Alternates paltP1
Re-positions otherwise monospace characters according to glyph width
Proportional Kana pknaS1
Kana for use alongside alphabets, without grid typography
Ruby Notation Forms rubyS1
Ruby characters , small print
Horizontal Kana Alternates hknaS1
Alternate forms for horizontal kana text, e.g. ー for chōonpu instead of ｜, cf. vkna
Vertical Kana vknaS1
Alternate Japanese kana forms for vertical text, e.g. ｜ for chōonpu instead of ー, cf. hkna
Centered CJK Punctuation cpctP1
Positions punctuation marks vertically and horizontally
[ edit ]
Long name tag type Description
Cursive Positioning cursP3
Precise positioning of a letter's connection to an adjacent one
Justification Alternates jaltS3
User selectable wider and narrower alternates, used especially for justifying
Mark Positioning via Substitution msetS5
Used in Windows 95 for positioning of Arabic marks
Required Contextual Alternates rcltS6
Contextual alternates required for correct text display which differs from the default join for other letters, required especially important by Arabic
Required Ligatures rligS3
Ligatures required for correct text display (any script, but in cursive)
Isolated Forms isolS1
Substitutes a special form of a letter occurring outside a word (required by Arabic and Syriac)
Initial Forms initS1
Substitutes a special form of a letter occurring at the beginning of a word (required by Arabic and Syriac)
Medial Forms mediS1
Substitutes a special form of letters between other letters in words (required by Arabic and Syriac)
Medial Form #2 med2S5
Syriac
Terminal Forms finaS1
Substitutes a special form of a letter at end of words (required by Arabic and Syriac)
Terminal Form #2 fin2S5
Syriac
Terminal Form #3 fin3S5
Syriac
Final Glyph on Line Alternates faltS3
Replaces final glyph on the line with an alternate
Stretching Glyph Decomposition stchS2
Substitutes a special form of a stretchy glyph onto one or more letters (required by Syriac)
[ edit ]
Long name tag type Description
Small Caps smcpS1
Replaces lower-case letters with small caps versions
Capitals to Small Caps c2scS1
Substitutes capital letters with small caps
Petite Caps pcapS1
Replaces lower-case letters with their petite caps analogs
Capitals to Petite Caps c2pcS1
Replaces capital letters with petite caps
Unicase unicS1
Replaces lowercase and uppercase letters with a set of single case glyphs
Capital Spacing cpspP1
Adjusts spacing between letters in all-capitals text
Case Sensitive Forms caseP1
Replace characters, especially punctuation, with forms better suited for all-capital text, cf. titl
Italics italS1
Replaces letter with corresponding italic glyph
Ordinals ordnS6,4
Replaces characters with ordinal forms for use after numbers
Features depending on writing direction [ edit ]
Long name tag type Description
Alternative Vertical Metrics valtP1
Positions shorter characters to be centered vertically with full-height characters
Alternative Vertical Half Metrics vhalP1
Positions characters to be centered vertically with half-height characters
Proportional Alternate Vertical Metrics vpalP1
Re-positions glyphs vertically to be centered on proportional full-height characters
Vertical Alternates vertS1
A subset of vrt2: prefer the latter feature
Vertical Alternates and Rotation vrt2S1
Replaces characters with forms suitable for vertical writing, possibly by rotating 90°
Vertical Alternates for Rotation vrtrS1
Replaces characters with forms suitable for vertical writing, possibly by shifting or shape
Vertical Kerning vkrnP2,8
Fine vertical positioning of characters based on shape
Left-to-right glyph alternates ltraS1
Replaces characters with forms befitting left-to-right presentation (except mirrored forms)
Left-to-right mirrored forms ltrmS1
Replaces characters with possibly mirrored forms befitting left-to-right presentation
Right-to-left glyph alternates rtlaS1
Replaces characters with forms befitting right-to-left presentation (except mirrored forms)
Right-to-left mirrored forms rtlmS1
Replaces characters with possibly mirrored forms befitting right-to-left presentation
Features intended for digits and math [ edit ]
Long name tag type Description
Lining Figures lnumS1
Replaces numerals with glyphs meant to fit better in all-capitals text, often also tnum
Oldstyle Figures onumS1
Replaces numerals with cased old-style numerals , often also pnum
Proportional Figures pnumS1
Replaces numerals with glyphs of proportional width, often also onum
Tabular Figures tnumS1
Replaces numerals with glyphs of uniform width, often also lnum
Fractions fracS4
Converts figures separated by slash with diagonal fraction
Alternative Fractions afrcS4
Converts figures separated by slash with alternative stacked fraction form
Denominator dnomS1
Converts to appropriate fraction denominator form, invoked by frac
Numerator numrS1
Converts to appropriate fraction numerator form, invoked by frac
Scientific Inferiors sinfS1
as in "H2 O", "SOx " or "YCb Cr " (but using the same font weight and predefined position in contrast these plain HTML subs and sups)
Slashed Zero zeroS1
Replaces 0 figure with slashed 0
Mathematical Greek mgrkS1
Replaces Greek characters with special forms for use in mathematics
Flattened accent forms flacThis feature is applied to individual glyphs during layout of math formula.
Dotless Forms dtlsThe dotless forms are to be used as base forms for placing mathematical accents over them.
Math script style alternates sstyThis feature can have a parameter indicating the script level: 1 for simple subscripts and superscripts, 2 for second level subscripts and superscripts (that is, scripts on scripts), and so on. (Currently, only the first two alternates are used). For glyphs that are not covered by this feature, the original glyph is used in subscripts and superscripts.
Long name tag type Description
Access All Alternates aaltS1,3
Special feature: used to present user with choice all alternate forms of the character
Swash swshS1,3
Either replaces character with or displays multiple swashed versions
Contextual Swash cswhS8
Converts letter to a swashed version based on characters around the letter
Contextual Alternates caltS6
Applies a second substitution feature based on a match of a character pattern within a context of surrounding patterns
Historical Forms histS1
Obsolete forms of characters to be applied at the user's discretion, cf. hlig
Localized Forms loclS1
Replaces character with the preferred form based on script language
Randomize randS3
Replaces character with random forms (meant to simulate handwriting)
Alternate Annotation Forms naltS1,3
Provides user access to circled digits, inverse letters etc.
Character Variant 1–99 cv01–S3
Multiple variants of a single character, which may not apply to many other characters, see references for voluminous documentation
Stylistic Alternates saltS1,3
Either replaces with, or displays list of, stylistic alternatives for a character
Stylistic Set 1 – 20 ss01-S1
Replaces character with one from a font-specific set of stylistic alternatives
Subscript subsS1
Replaces character with subscript version, cf. numr
Superscript supsS1
Replaces character with superscript version, cf. dnom
Titling Alternates titlS1
Replaces characters with forms suited for large type, as in titles
Required Variation Alternates rvrnS1
Special variants of a single character, which need apply to specific font variation, required by variable fonts
Contextual Ligatures cligS8
Applies a second ligature feature based on a match of a character pattern within a context of surrounding patterns
Discretionary Ligatures dligS4
Ligatures to be applied at the user's discretion
Historical Ligatures hligS1
Obsolete ligatures to be applied at the user's discretion
Standard Ligatures ligaS4
Replaces (by default) sequence of characters with a single ligature glyph
Positioning features intended for all scripts [ edit ]
Long name tag type Description
Glyph Composition/Decomposition ccmpS4,2
Either calls a ligature replacement on a sequence of characters or replaces a character with a sequence of glyphs. Provides logic that can for example effectively alter the order of input characters.
Kerning kernP2,8
Fine horizontal positioning of one glyph to the next, based on the shapes of the glyphs
Mark Positioning markP4,5
Fine positioning of a mark glyph to a base character
Mark-to-mark Positioning mkmkP6
Fine positioning of a mark glyph to another mark character
Optical Bounds opbdP1
Re-positions glyphs at beginning and end of line, for precise justification of text.
Left Bounds lfbdP1
Re-positions glyphs at end of line. Called by opbd.
Right Bounds rtbdP1
Re-positions glyphs at beginning of line. Called by opbd.
Special features intended for all scripts [ edit ]
Long name tag type Description
Optical size sizeNot a lookup: feature's table provides to applications information about the appearance and intent of the font, to aid in font selection.
Ornaments ornmS3,1
Decorative alternates for the bullet character •
Legend of substitution and positioning codes [ edit ] Below are listed the OpenType lookup table types, as used in the "type" column in the above tables. S stands for substitution , and P stands for positioning . Note that often a feature can be implemented by more than one type of table, and that sometimes the specification fails to explicitly indicate the table type.
abbrev. type description
S1 GSUB 1 simple substitution of one glyph for another
S2 GSUB 2 multiple replacement of one character by several glyphs
S3 GSUB 3 variant selection
S4 GSUB 4 ligatures
S5 GSUB 5 contextual substitution
S6 GSUB 6 chained contextual substitution
S7 GSUB 7 extension for GSUB tables past 64kB
S8 GSUB 8 reverse chained contextual substitution
P1 GPOS 1 positioning of single glyph
P2 GPOS 2 positioning of pair of glyphs
P3 GPOS 3 cursive attachment
P4 GPOS 4 positioning of mark glyphs relative to base
P5 GPOS 5 positioning of mark glyphs relative to ligature
P6 GPOS 6 positioning of mark glyphs relative to another mark glyph
P7 GPOS 7 contextual positioning
P8 GPOS 8 extended contextual positioning
P9 GPOS 9 extension for GPOS tables past 64kB
AAT typographic features [ edit ] Features that take one value, mutual exclusive from the rest:
Annotation nalt
No Annotation
Box Annotation
Rounded Box Annotation
Circle Annotation
Inverted Circle Annotation
Parenthesis Annotation
Period Annotation
Roman Numeral Annotation
Diamond Annotation
Character Alternatives
No Alternates ... rand; aalt, calt, falt, jalt, salt, ssXX, hkna/vkna, rtla, vrt2
Character Shape half, ruby; ljmo, vjmo, tjmo
Traditional Characters trad
Simplified Characters smpl
JIS 1978 Characters jp78
JIS 1983 Characters jp83
JIS 1990 Characters jp90
Traditional Characters, Alternative Set 1...5 tnam, hojo, nlck
Expert Characters expt, locl
CJK Latin Spacing
Half-width hwid, halt
Proportional pwid, palt
Default Latin
Full-width Latin fwid
Cursive Connection init, medi/med2, fina/fin2/fin3; haln, nukt, vatu, rphf, pres, pstf/psts
Unconnected isol
Partially Connected calt, clig
Cursive curs
Design Complexity
Design Level 1 Design Level ...
Diacritics
Show Diacritics Hide Diacritics
Decompose Diacritics ccmp
Fractions
No Fractions
Vertical Fractions afrc
Diagonal Fractions frac, dnom, numr
Ideographic Spacing
Full Width fwid
Proportional pwid, palt
Kana Spacing
Full Width fwid
Proportional pwid, palt
Letter Case case
Upper & Lower Case All Caps
All Lower Case
Small Caps smcp, pcap
Initial Caps c2sc, c2pc
Initial Caps and Small Caps
Number Case
Lower Case Numbers onum
Upper Case Numbers lnum
Number Spacing
Monospaced Numbers tnum
Proportional Numbers pnum
Ornament Sets ornm
None Dingbats
Pi Characters
Fleurons
Decorative Borders
International Symbols
Math Symbols mgrk
Text Spacing
Proportional pwid, palt
Monospace fwid
Half-width hwid, halt
Normal
Vertical Position
No Vertical Position Superiors sups
Inferiors subs, sinf
Ordinals ordn Features that take a number of values:
Ligatures
Required Ligatures rlig, clig
Common Ligatures liga
Rare Ligatures hlig, dlig
Logos
Rebus Pictures
Diphthong Ligatures
Squared Ligatures
Squared Ligatures, Abbreviated Mathematical Extras
Hyphen to Minus (‘-’ → ‘−’)
Asterisk to Multiply (‘*’ → ‘×’)
Slash to Divide (‘/’ → ‘÷’)
Inequality Ligatures
Exponents
Smart Swashes swsh, cswh
Word Initial Swashes
Word Final Swashes
Line Initial Swashes
Line Final Swashes falt
Non-Final Swashes jalt
Style Options
No Style Options Display Text size
Engraved Text
Illuminated Caps
Titling Caps titl
Tall Caps
Transliteration locl
Typographic Extras
Hyphens to Em Dash (‘--’ → ‘—’)Hyphen to En Dash (‘-’ → ‘–’)
Unslashed Zero zero
Form Interrobang (‘!?’/‘?!’ → ‘‽’)
Smart Quotes (‘"'"’ → ‘“’”’)
Periods to Ellipsis (‘...’ → ‘…’ ) Binary features that can only be turned on:
All Typographic Features
Linguistic Rearrangement
Overlapping Characters
Vertical Substitution
