Description
I'm not sure exactly how to point to the spec about this...
I did some thinking on Twitter a few minutes ago:
I say “anchor typeface” to refer to a choice of font (usually body text font) around which you make other decisions (type palette, layout). I’m thinking of saying “anchor point” to refer to a specific point in a variable font’s design space. The point around which it flexes. As a typographer, I might choose the default instance of a variable font (Regular weight/width) as my anchor point — or I might choose a different, unnamed instance. And from there, I would respond to pressure by moving along various axes relative to that anchor point.
By this logic, I might want to specify flexibility and responsiveness relative to the anchor point, instead of picking absolute coordinates in the design space. In the same way that em-based measurements are affected by changing the value to which they all refer, positions along various axes in a variable font would be affected by changing the anchor point to which they refer.