What PDF standard should be used when exporting or saving as PDF?

Over the last decade there has been a significant growth in the use of PDF for transferring graphic arts content files between sites and between companies. As the growth of PDF use has continued it has become increasingly clear that the PDF file format alone is simply too flexible to enable robust and predictable exchanges of pre-press data.

A family of international standards has therefore been developed to define restrictions on the content and use of PDF files to make print output more predictable. These standards are collectively called PDF/X, each with a suffix to differentiate the specifications defined for different sets of market needs. Each is published in a part of International Standard ISO 15930.

Save your File as PDF/X-1a

PDF/X-1a is designed to provide the most robust and, to some extent, least flexible delivery of PDF content data. It requires that the color of all objects be expressed in CMYK or spot colors, all prepared for the print conditions under which the final press-work will be run. Elements in RGB and Lab color spaces or tagged with ICC profiles are prohibited. It also requires that all fonts used in the job be embedded in the supplied PDF file and disallows the use of transparency and layers (optional content).