Ensures that if an object is set to overprint, it overprints on all separations. You can apply the overprint to the fill color and/or the stroke color.
The overprint rules in PDF are clearly defined but sometimes very surprising. For example, a gray object that is set to overprint will overprint on underlying Pantone colors, but it will not overprint on Cyan, Magenta and Yellow. This Action will ensure that the document will still print as Black, but with overprint on CMY.