Lingua Franca is a serif font family based on the Heuristica font family, which in turn is based on the Utopia Type 1 fonts, designed by Robert Slimbach.
Lingua Franca fonts are particularly useful for documents in linguistics. The regular typeface includes all characters of the Unicode IPA extensions as well as many spacing or combining diacritics. In addition, the typefaces support various typographic features such as ligatures, proportional figures etc.; a stylistic set provides longer slashes, matching the parentheses in height and depth.