An outline font stores glyph shapes as geometric boundaries that can be scaled before drawing. Bézier curves provide editable segments of these boundaries. TrueType outlines use quadratic Bézier curves; Type 2 charstrings used in Compact Font Format outlines use cubic Bézier curves. [ref]
https://learn.microsoft.com/en-us/typography/opentype/spec/ttch01. OpenType specification, TrueType fundamentals: outlines
[ref]https://adobe-type-tools.github.io/font-tech-notes/pdfs/5177.Type2.pdf. Adobe, The Type 2 Charstring Format, section 4.1
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