Jeff Allen wrote:
For a kitchen sink that requires a worktop cut-out size of
980x480 (cr=20) what does "cr=20" mean here?

Corner radius ? The cutout is not a full rectangle and a 20mm radius
on the corners sounds about right. You would measure out the enclosing
rectangle, though, and cut a smooth quarter turn from 20mm in, on both
sides.

[I'm guessing, btw.]

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