Ghent, Belgium -- April 10, 2008 -- PDF file integrity can now be easily verified as a result of The Ghent Workgroup's (GWG) release of the first free "Proof of Preflight" specification.  When implemented in a software solution, this best practice specification offers users the ability to review a PDF file's preflight audit trail, including a digital signature, at any time during the design to print workflow.
 
This capability provides users the assurance that they can safely accept a PDF file with a Proof of Preflight.  This process verifies which GWG preflight Specification was used to preflight the file and also the outcome of the preflight check.
 
Another key benefit of the GWG Proof of Preflight specification is its "open" design, making it interoperable across different vendor workflows.  GWG designed the digital signature using algorithms which are defined in the PDF 1.7 (or earlier) specification(s), and which are supported in Acrobat as of Acrobat 8. The digital signature complies with all requirements present in the PDF/X-1a and PDF/X-3, and PDF/X-4 standards.
 
The Ghent Workgroup is an international cross-section of PDF and print experts known for creating, testing, and releasing specifications and best practices that have been proven to make it easier for users to ensure PDF document quality across workflows around the world.  This first version of its free Proof of Preflight specification was developed by the GWG Process Control Subcommittee.  This committee is chaired by Andy Psarianos, F E Burman; with contributions from Olaf Drümmer, Callas, (who was instrumental in the specification documentation); Leonard Rosenthal, Adobe; Peter Kleinheider, Callas; Stephane Georges, Dalim; and Stephan Jaeggi, Pre-Press Consulting. The goal of the Process Control subcommittee is to increase the already high level of predictability in PDF workflows by delivering best practice guidelines for the testing and evaluation of PDF reading applications.
 
GWG Proof of Preflight Developed at the Request of Real World Users
Jo Brunenberg, Senior Technology Consultant for ROTO SMEETS (RSDB), says, "At our Roto Smeets printing locations, which includes 2 gravure, 3 web offset and 3 sheetfed plants, we receive thousands of PDFs every day through automated submission systems. A substantial part of the submitted PDFs have been successfully preflighted by the client using the correct GWG PDF profiles, although others have not been preflighted at all.  Of course we advise our clients to perform PDF preflighting before submission and many clients do this in a very professional way but, unfortunately not all of them do so. So we have to check all submitted PDF's again to make sure we do not pass technical problems along to the production department."
 
"The ability to include a Proof of Preflight in each PDF, specify if the PDF was preflighted and if so, what PDF profile was used; and to even review the preflight result, will enable our automated workflows to sort out PDFs that are already perfectly OK and PDFs that still need attention or checking. This will increase the efficiency of our automated workflows by skipping unnecessary secondary preflights. Also the added metadata will enable us to analyze problems, if any, more quickly. I am glad that the GWG with the support of Adobe and the other GWG vendor members has been willing to design the technical concept of such a Proof of Preflight that will automatically insert the necessary metadata in the PDF upon preflight. Hopefully all major preflight software vendors are going to implement this valuable solution in their applications in order to improve the efficiency and transparency of the print production chain."
How the GWG Proof of Preflight Specification Works in Practice:
1. A sender executes a preflight check for sending out the PDF file
 
2. Using Proof of Preflight, he/she can sign off on the file and by doing so state:
 
a. I did run a preflight check
b. I used the following profile (identified by name)
c. the results I got were ______
d. please make sure you get the file as I sent it
 
3.  If someone wants to verify the sender's statements, he/she can view the Proof of Preflight information to determine:
 
a. if an audit trail was embedded
b. if a GWG profile was used (identified by its name)
c. whether that profile is exactly the same as some other known profile
d. the results from executing the profile (no errors or number of errors)
e  whether the PDF has been modified since embedding the Proof of Preflight audit trail
 
The GWG Proof of Preflight specification is available immediately and can be downloaded for free at: www.gwg.org.