Depends, there are 2 proofs, There is what's called "Color Keys" or "Go Bys" each shop may have a different terminology but result is the same. The color keys are what the press operator uses and looks at to try and match the color to, ya know, what shade of blue does Marvel want, what shade of red ect... But sometimes they have a sample copy, basically a finished copy that another print shop may have printed that they'll use as the "color key" it also shows the press operator what the customer (Marvel) wants the book to look like in terms of color, register, trim size, ect...basically "Make every book like like this one"