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.

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.

Full Width

Tag: fwid

Function: Replaces glyphs set on other widths with glyphs set on full (usually em) widths. In a CJKV font, this may include "lower ASCII" Latin characters and various symbols. In a European font, this feature replaces proportionally-spaced glyphs with monospaced glyphs, which are generally set on widths of 0.6 em. The user may invoke this feature in a Japanese font to get full monospaced Latin glyphs instead of the corresponding proportionally-spaced versions.

Half Width

Tag: hwid

Function: Replaces glyphs on proportional widths, or fixed widths other than half an em, with glyphs on half-em (en) widths. Many CJKV fonts have glyphs which are set on multiple widths; this feature selects the half-em version. There are various contexts in which this is the preferred behavior, including compatibility with older desktop documents. The user may replace a proportional Latin glyph with the same character set on a half-em width.

Proportional Widths

Tag: pwid

Function: Replaces glyphs set on uniform widths (typically full or half-em) with proportionally spaced glyphs. The proportional variants are often used for the Latin characters in CJKV fonts, but may also be used for Kana in Japanese fonts. The user may invoke this feature in a Japanese font to get a proportionally-spaced glyph instead of a corresponding half-width Roman glyph or a full-width Kana glyph.

Traditional Forms

Tag: trad

Function: Replaces 'simplified' Chinese hanzi or Japanese kanji forms with the corresponding 'traditional' forms. The user inputs U+53F0 and is offered a choice of U+6AAF, U+81FA, or U+98B1.

Vertical Writing

Tag: vert

Function: Replaces default forms with variants adjusted for vertical writing when in vertical writing mode. While most CJKV glyphs remain vertical when set in vertical writing mode, some take a different form (usually rotated and repositioned) for this purpose. Glyphs covered by this feature correspond to the set normally rotated in low-end DTP applications. In vertical writing mode, the opening parenthesis (U+FF08) is replaced by the rotated form (U+FE35).

Vertical Rotation

Tag: vrt2

Function: Replaces some fixed-width (half-, third- or quarter-width) or proportional-width glyphs (mostly Latin or katakana) with forms suitable for vertical writing (that is, rotated 90 degrees clockwise). Note that these are a superset of the glyphs covered in the vert table. ATM/NT 4.1 and the Windows 2000 OTF driver impose the following requirements for an OpenType font with CFF outlines to be used for vertical writing: the vrt2 feature must be present in the GSUB table, it must comprises a single lookup of LookupType 1 and LookupFlag 0, and the lookup must have a single subtable. The predecessor feature, vert, is ignored. A rotated glyph must be designed such that its top side bearing and vertical advance as recorded in the Vertical Metrics ('vmtx') table are identical to the left side bearing and horizontal advance, respectively, of the corresponding upright glyph as recorded in the Horizontal Metrics ('hmtx') table. (The horizontal advance of the rotated glyph may be set to any value, since the glyph is intended only for vertical writing use. The vendor may however set it to head.unitsPerEm, to prevent overlap during font proofing tests, for example.) Thus, proportional-width glyphs with rotated forms in the vrt2 feature will appear identically spaced in both vertical and horizontal writing. In order for kerning to produce identical results as well, developers must ensure that the Vertical Kerning (vkrn) feature record kern values between the rotated glyphs that are the same as kern values between their corresponding upright glyphs in the Kerning (kern) feature. Proportional- or half-width Latin and half-width katakana characters are rotated 90 degrees clockwise for vertical writing.

Alternate Annotation Forms

Tag: nalt

Function: Replaces default glyphs with various notational forms (e.g. glyphs placed in open or solid circles, squares, parentheses, diamonds or rounded boxes). In some cases an annotation form may already be present, but the user may want a different one. The user invokes this feature to get U+3200 (the circled form of 'ga') from U+3131 (hangul 'ga').

Simplified Forms

Tag: smpl

Function: Replaces 'traditional' Chinese or Japanese forms with the corresponding 'simplified' forms. The user gets U+53F0 when U+6AAF, U+81FA, or U+98B1 is entered.

Tag: lowercase

Function:

Tag: uppercase

Function: