PATH Mac OS 8 and 9 Developer Documentation > Text and Other International Services > Apple Type Services for Unicode Imaging (ATSUI) > Apple Type Services for Unicode Imaging Reference

Ligature Font Feature Selector Constants

If the font supports the ligatures feature type, you can select features related to ligature formation, such as those shown in Table D-14.

Table D-14 Feature selectors for the kLigaturesType feature type

Constant	Explanation
`kRequiredLigaturesOnSelector kRequiredLigaturesOffSelector`	Allows or prevents the use of ligatures that the font designates as required by the language (such as certain Arabic ligatures).
`kCommonLigaturesOnSelector kCommonLigaturesOffSelector`	Allows or prevents the use of ligatures that the font designates as "common," or normally used (such as the "fi" ligature in Roman text).
`kRareLigaturesOnSelector kRareLigaturesOffSelector`	Allows or prevents the use of ligatures that the font designates as "rare" (such as "ct" or "ss" ligatures).
`kLogosOnSelector kLogosOffSelector`	Allows or prevents the use of ligatures that the font designates as logotypes (typically used for trademarks or other special display text).
`kRebusPicturesOnSelector kRebusPicturesOffSelector`	Allows or prevents the use of rebuses (pictures that represent words or syllables).
`kDiphthongLigaturesOnSelector kDiphthongLigaturesOffSelector`	Specifies whether or not to replace diphthong sequences, such as "AE" and "oe", with their equivalent ligatures ("Æ" and "?" in this case).
`kSquaredLigaturesOnSelector kSquaredLigaturesOffSelector`	Allows or prevents the use of ligatures where the component letters are arranged in a lattice, such that the ligature fits into the space of a single letter. For examples, see Unicode characters `U+3300` through `U+3357` and `U+337B` through `U+337F`.
`kAbbrevSquaredLigaturesOnSelector kAbbrevSquaredLigaturesOffSelector`	Allows or prevents the use of ligatures similar to the previously described ligatures, but in abbreviated form.

Figure D-6 shows several levels of ligature formation specified through ligature feature selectors.

Figure D-6 Levels of ligature formation controlled with ligature feature selectors

Figure D-7 shows the results of selection (upper) and deselection (lower) of diphthong ligatures.

Figure D-7 Use of diphthong ligatures