Checks the number of separations that occur in a PDF file. You can set a precise number (e.g. 5 separations) or a range (e.g. less than 5) and choose whether or not to exclude certain colors (e.g. CMYK plates, spot color All ...).
ICC tagging is a way to specify colors independent from the output device: objects are tagged with an ICC profile that contains the transformation from the object's color to a device-independent color. When outputting this on a specific device, that device-independent color is in turn converted to the output device's color space.
Because this conversion depends on the output device, and because it will rarely (if ever) result in less than 4 color plates being used, checking the number of separations on an ICC tagged object will always result in 4 separations.
For example, if you have a black (100% K) ICC tagged object, the number of separations reported by this Action will be 4 (C, M, Y, K) instead of 1 (only K) because some ink will be used on all plates in order to reproduce the color correctly.