A superfamily is a set of typefaces released under a common trade name that combines several families across stylistic classes. Members of a typeface superfamily differ not only in weight, width, inclination, Optical Size and character sets, but also in other design characteristics such as stroke modulation and treatment of serifs — but still share certain other characteristics such as proportions, which allows them to work together. ITC Stone Sans, ITC Stone Serif, ITC Stone Informal and ITC Stone Humanist are four families that form a superfamily.
Family that Contains Both Serif and Sans Serif
Poll: The best term for a type family that includes both serif and sans serif fonts is?
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Superfamilies (listing of superfamilies)
My Type Design Philosophy by Martin Majoor
Serial Type Families (PDF) by Alejandro Lo Celso
fy(t)i: Super Families
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List of Superfamilies with Samples