If your pages are to be
printed in the four process colours and are not intended to
print with any extra colours (spot colours) you must be
really careful not to inadvertently include any spot
colours on your pages where transparency is used.
The flattening process handles spot colours in a special
way and with overprints, and if a flattened file which
includes spot colour is presented to a CMYK workflow, which
will convert the flattened spot colour to CMYK it will
probably not reproduce as expected. Only incorporate spot colours in your
layout if you know they will be used on the press.
Be careful
when mixing overprinting and spot colours with
transparency. To view the printed results of overprinting
on-screen, enable Overprint Preview.
