What is: Progressive Color Proofs (Prongs) ?

Proofs of color separation negatives which had prior exposure to offset plates and are printed using process inks. They are printed in sequence, i.e., 1. Red plate alone. 2. Yellow plate alone. 3. Blue alone. 4. Black alone. 5. Red and yellow. 6. Red, yellow, and blue. 7. Red, yellow, blue, and black. It is an effective way of checking the color of desperation negatives which use the same color sequence, paper, ink, and ink densities intended for a production run.