What does 4/0, 4/1 & 4/4 printing mean?

4/0 refers to full color printing on one side of the printed page. 4/1 refers to full color printing on one side and black printing on the other side. 4/4 refers to full color printing on both sides. If you want just one color ( beside black ) on the sheet when one side is full color, the one color is made up of CMYK and it would be a 4/4 printed product even though it looks like one color. CMYK is the abbreviation for Cyan, Magenta, Yellow, and Key (Black). This is the industry standard process colors used in full color offset printing. The combination of these four colors can produce a wide array of colors.. 4/0/, 4/1 or 4/4 can also mean the same thing for spot color.