I have little experience with CUPS, but I do know this: CUPS uses Adobe Distiller to generate its PDF files, and PlanetPress uses the Adobe PDF engine to process PDF files.
Therefore, I don't foresee any issue with the latter processing the former.
Ask your customer to provide you with a sample PDF, or better yet, have them install an evaluation version of the PlanetPress Design tool and have them drag&drop one of those PDFs onto the Data Pane. They will instantly know whether it works or not.
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Technical Product Manager
I don't want to achieve immortality through my work; I want to achieve immortality through not dying - Woody Allen