What PDF Format Should I Use?

We feel that the PDF 1.5 (Acrobat 6.0) format provides the best combination of backwards compatibility and features needed for CAD users and should be your default format unless your customer's specifications call for a different version.

PDF 1.5 (Acrobat 6.0) includes support for transparency (lines merge), 128 bit encryption, and layers.

The PDF/A formats specifically PDF/A-1a and PDF/A-1b originally did not support transparency or layers.  Because of this we suggest that if you have to use the PDF/A format that you use the PDF/A-2 variants if your clients specifications allow it.