Capital SpacingGlobally adjusts inter-glyph spacing for all-capital text. Most typefaces contain capitals and lowercase characters, and the capitals are positioned to work with the lowercase. When capitals are used for words, they need more space between them for legibility and esthetics. This feature would not apply to monospaced designs. Of course the user may want to override this behavior in order to do more pronounced letterspacing for esthetic reasons.
DenominatorsReplaces selected figures which follow a slash with denominator figures.
Terminal FormsReplaces glyphs at the ends of words with alternate forms designed for this use. This is common in Latin connecting scripts, and required in various non-Latins like Arabic.
FractionsReplaces figures separated by a slash with 'common' (diagonal) fractions.
Initial FormsReplaces glyphs at the beginnings of words with alternate forms designed for this use. This is common in Latin connecting scripts, and required in various non-Latins like Arabic.
Standard LigaturesReplaces 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.
NumeratorsReplaces selected figures which precede a slash with numerator figures, and replaces the typographic slash with the fraction slash.
OrdinalsReplaces 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.
Scientific InferiorsReplaces lining or oldstyle figures with inferior figures (smaller glyphs which sit lower than the standard baseline, primarily for chemical or mathematical notation). May also replace lowercase characters with alphabetic inferiors.
SuperscriptReplaces lining or oldstyle figures with superior figures (primarily for footnote indication), and replaces lowercase letters with superior letters (primarily for abbreviated French titles).
