Earlier quoted context omitted.
> appealing to programmers because they seem intuitively like the "right" solution … Constraints don't match the way designers work Interesting, I'd say almost the opposite. These constraints capture almost exactly the same thing as the orange guide lines you see in Keynote (or Powerpoint, or whatever). This is inset from the top right by 10, this button is the same width as the one above, the distance between these…
> That's almost exactly what designers' specs look like in my experience – screenshots annotated with lines with numbers on 'em. Yes, but that's because those designers were asked to specify the layout in engineer terms. :) That doesn't mean that that's the way they think and conceive the UI.
And some designers tools also let them express it in exactly that way.