It's all about flattening. Flattening is the process of replicating the look of transparency using non-transparent objects. Flattening involves converting parts of a transparency effect into bitmap or vector objects that, when printed, will give the appearance of transparency. The deal is that PostScript does not support live (unflattened) transparency. So when you create an EPS file of a document that contains transparency, the transparency will be flattened at the time the EPS file is created.PDF versions 1.4 and later, on the other hand, support live transparency, which means that they can store information about the transparency without the need to flatten it at the time the PDF file is created. In either case, of course, transparency has to be flattened before it can be printed.The advantage of using PDF over EPS for a file that contains transparency is that the flattening can take place late in the production process--allowing you to choose the flattening settings when you are sure of the press and paper on which the job will be printed. So, you can still use EPS files, you just will have to decide on the flattening settings when the EPS file is created...which may, or may not, be an issue in your particular workflow. I hope this helps!-- Jim Birkenseer