Access All Alternates

Tag: aalt

Function: This feature makes all variations of a selected character accessible. This serves several purposes: An application may not support the feature by which the desired glyph would normally be accessed; the user may need a glyph outside the context supported by the normal substitution, or the user may not know what feature produces the desired glyph. Since many-to-one substitutions are not covered, ligatures would not appear in this table unless they were variant forms of another ligature. A user inputs the P in Poetica, and is presented with a choice of the four standard capital forms, the eight swash capital forms, the initial capital form and the small capital form.

Standard Ligatures

Tag: liga

Function: Replaces a sequence of glyphs with a single glyph which is preferred for typographic purposes. This feature covers the ligatures which the designer/manufacturer judges should be used in normal conditions. The glyph for ffl replaces the sequence of glyphs f f l.

Lining Figures

Tag: lnum

Function: This feature changes selected figures from oldstyle to the default lining form. The user invokes this feature in order to get lining figures, which fit better with all-capital text. Various characters designed to be used with figures may also be covered by this feature. In cases where lining figures are the default form, this feature would undo previous substitutions.

Localized Forms

Tag: locl

Function: Many scripts used to write multiple languages over wide geographical areas have developed localized variant forms of specific letters, which are used by individual literary communities. For example, a number of letters in the Bulgarian and Serbian alphabets have forms distinct from their Russian counterparts and from each other. In some cases the localized form differs only subtly from the script 'norm', in others the forms are radically distinct. This feature enables localized forms of glyphs to be substituted for default forms. The user applies this feature to text to enable localized Bulgarian forms of Cyrillic letters; alternatively, the feature might enable localized Russian forms in a Bulgarian manufactured font in which the Bulgarian forms are the default characters.

Old Style Figures

Tag: onum

Function: This feature changes selected figures from the default lining style to oldstyle form. The user invokes this feature to get oldstyle figures, which fit better into the flow of normal upper- and lowercase text. Various characters designed to be used with figures may also have oldstyle versions.

Ordinals

Tag: ordn

Function: Replaces default alphabetic glyphs with the corresponding ordinal forms for use after figures. One exception to the follows-a-figure rule is the numero character (U+2116), which is actually a ligature substitution, but is best accessed through this feature. The user applies this feature to turn 2.o into 2.o (abbreviation for secundo).

Stylistic Alternates

Tag: salt

Function: Many fonts contain alternate glyph designs for a purely esthetic effect; these don't always fit into a clear category like swash or historical. As in the case of swash glyphs, there may be more than one alternate form. This feature replaces the default forms with the stylistic alternates. The user applies this feature to Industria to get the alternate form of g.

Discretionary Ligatures

Tag: dlig

Function: Replaces a sequence of glyphs with a single glyph which is preferred for typographic purposes. This feature covers those ligatures which may be used for special effect, at the user's preference. The glyph for ct replaces the sequence of glyphs c t, or U+322E (Kanji ligature for "Friday") replaces the sequence U+91D1 U+66DC U+65E5.

Sylistic Set 1

Tag: ss01

Function: In addition to, or instead of, stylistic alternatives of individual glyphs (see 'salt' feature), some fonts may contain sets of stylistic variant glyphs corresponding to portions of the character set, e.g. multiple variants for lowercase letters in a Latin font. Glyphs in stylistic sets may be designed to harmonise visually, interract in particular ways, or otherwise work together. Examples of fonts including stylistic sets are Zapfino Linotype and Adobe's Poetica. Individual features numbered sequentially with the tag name convention 'ss01' 'ss02' 'ss03' . 'ss20' provide a mechanism for glyphs in these sets to be associated via GSUB lookup indexes to default forms and to each other, and for users to select from available stylistic sets.

Sylistic Set 2

Tag: ss02

Function: In addition to, or instead of, stylistic alternatives of individual glyphs (see 'salt' feature), some fonts may contain sets of stylistic variant glyphs corresponding to portions of the character set, e.g. multiple variants for lowercase letters in a Latin font. Glyphs in stylistic sets may be designed to harmonise visually, interract in particular ways, or otherwise work together. Examples of fonts including stylistic sets are Zapfino Linotype and Adobe's Poetica. Individual features numbered sequentially with the tag name convention 'ss01' 'ss02' 'ss03' . 'ss20' provide a mechanism for glyphs in these sets to be associated via GSUB lookup indexes to default forms and to each other, and for users to select from available stylistic sets.

Glyph Composition/Decomposition

Tag: ccmp

Function: To minimize the number of glyph alternates, it is sometimes desired to decompose a character into two glyphs. Additionally, it may be preferable to compose two characters into a single glyph for better glyph processing. This feature permits such composition/decompostion. The feature should be processed as the first feature processed, and should be processed only when it is called. In Syriac, the character 0x0732 is a combining mark that has a dot above AND a dot below the base character. To avoid multiple glyph variants to fit all base glyphs, the character is decomposed into two glyphs...a dot above and a dot below. These two glyphs can then be correctly placed using GPOS. In Arabic it might be preferred to combine the shadda with fatha (0x0651, 0x064E) into a ligature before processing shapes. This allows the font vendor to do special handling of the mark combination when doing further processing without requiring larger contextual rules.

Tag: lowercase

Function:

Tag: uppercase

Function: