Apple Advanced Typography

AAT font features do not alter the underlying typed text; they only affect the characters' representation during glyph conversion.

The cross-platform ICU library provided basic AAT support for left-to-right scripts.

As of OS X Yosemite and iOS 8, AAT supports language-specific shaping—that is, changing how glyphs are processed depending on the human language they are being used to represent.

[3] Provision was added at the same time for the relative positioning of two glyphs via anchor points via the 'kerx' and 'ankr' tables.

Features can be made invisible to the user by the simple expedient of not including entries in the "feat" table for them.

The font designer is also responsible for making sure that "morx" subtables are ordered correctly for the desired effect.

AAT operates entirely with glyphs and never with characters, so all the layout information necessary for producing the proper display resides within the font itself.

Third parties can produce fonts for scripts not officially supported by Apple, and they will work with macOS.

Zapfino, Hoefler Text, and Skia are fonts that ship with macOS that illustrate a variety of AAT's capabilities.

As noted above, OpenType fonts for Indic scripts require AAT tables to be added before they will function properly on macOS.

Mac OS X 10.5 shipped with fonts for Devanagari, Gurmukhi, Gujarati, Thai, Tibetan, and Tamil.

Fonts for other Indic scripts were included in later versions of macOS and iOS, as well as being available from third parties.