The PDF/VT Standard

The PDF/VT standard has been published in 2010 as ISO 16612-2010. It is »designed to enable variable document printing (VDP) in a variety of environments«. (Note that the abbreviation VDP is sometimes expanded to »Variable Data Printing« as an alternative to »Variable Document Printing«). PDF/VT documents contain the final content elements and associated metadata, but not any variables or templates. The predecessor standard ISO 16612-1:2005 specified the PPML/VDX formats based on PDF 1.4. However, this older standard was missing several PDF features and relied on constructs external to PDF. The modern PDF/VT standard is based on PDF/X-4 and PDF/X-5 and supports PDF 1.6 features including transparency, layers, and ICC-based color management. In addition to the requirements of PDF/X the PDF/VT standard adds supplementary features to PDF to meet the requirements of high-volume personalized printing. PDF/VT enables high-performance rendering (ripping) of digital print files by adding efficient resource management to PDF.

Since PDF/X includes color management features and support for ICC color profiles, PDF/VT inherits the same features. While color management may present a learning curve for organizations which up to now restricted themselves to black and white printing, it opens up the arena for colorful print products with consistent color reproduction.

The scope of PDF/VT includes the important segments »variable document printing« and »transactional printing« which are defined below.

Variable data printing

Variable data printing (variable document printing, VDP) – also called personalized or one-to-one marketing – generates individualized pages, i.e. some or all printed pages are different. Variable content is taken from a database and used to customize each document. VDP is mainly used for marketing purposes since personalized documents catch the recipient’s attention much faster than unpersonalized mass mailings. Some examples:

Business correspondence with variable name and address information.

Customized brochures with variable text and graphics elements, where the variable elements are selected based on a set of composition rules. As a result, graphically rich and unique documents are created.

Truly personalized offerings where the actual contents vary based on the location, sex, age, purchasing history or other known information about the recipient.

Transactional printing

Transactional printing produces records of a purchase, account, or other transaction, such as bills, statements and policies. If promotional or marketing messages are included in the transactional document the combination is called transactional-promotional, or transpromo. Common industry-specific examples:

Financial services sector: a financial statement includes customized offers tailored to the individual recipient.

Utility sector: an electricity or gas bill contains customized service offerings based on the customer's actual consumption.

Telecommunications sector: a phone bill includes custom discount offers based on the specific type and number of phone connections the customer had in the previous month.

Conformance levels: PDF/VT-1, PDF/VT-2, and PDF/VT-2s

ISO 16612-2 specifies three PDF/VT conformance levels, all of which are based on PDF 1.6:

PDF/VT-1 is designed for single-file exchange and based on PDF/X-4. All resources required for rendering a PDF document are contained in a self-contained PDF/VT-1 file. For this reason PDF/X-4p with external output intents is not allowed.

PDF/VT-2 is designed for multi-file exchange and based on one of the standards PDF/X-4p, PDF/X-5g, or PDF/X-5pg. PDF/VT-2 documents can reference external output intents, external page contents, or both. A PDF/VT document and all its referenced PDF files and external output intents are collectively called a PDF/VT-2 file set.

PDF/VT-2s is designed for streamed delivery where document generation and rendering can be interleaved. A PDF/VT-2s stream is a MIME package containing one or more PDF/VT-1 files or PDF/VT-2 file sets (or both flavors) plus all referenced files.

Referenced pages in Acrobat

Referenced pages are a crucial component of PDF/ X-5g and PDF/X-5pg and therefore also PDF/VT-2. In order to display referenced pages it is important to properly configure Acrobat as follows (the document which includes external references is called the container document; the external PDF with the referenced page(s) is called the target file):

Edit, Preferences, General..., Page Display, Show reference XObject targets: set to Always (the setting Only PDF-X/5 compliant ones doesn’t work due to a bug in Acrobat X/XI/ DC).

Edit, Preferences, General..., Page Display, Location of referenced files: enter the name of the directory where the target files live.

Edit, Preferences, General..., Security (Enhanced), Privileged Locations, Add Folder Path: add the name of the directory where the container documents live. This must be done regardless of the Enable Enhanced Security setting.

The target page, whose file name and page number are specified inside the container PDF, will be displayed instead of the proxy if all of the following conditions are true:

The container document is trusted according to Acrobat’s configuration;

The target file can be found in the specified directory;

The target file does not require any password and can be opened without errors.

The page number of the referenced page specified in the container document exists in the target file.

PDF/X-5 only: the ID and certain XMP metadata entries in the target must match the corresponding entries in the container document.

If one or more of these conditions are violated, the proxy will silently be  displayed instead of the target page. Acrobat does not issue any error message.

More Information

The PDFlib Whitepaper »A Technical introduction to PDF/VT« explains the technical concepts which are specified in PDF/VT on top of PDF/X-4 and PDF/X-5.

During our implementation of PDF/VT support in PDFlib we collected various notes on the ISO 16612-2:2010 document. These range from minor editorial changes to technical errors and a few suggestions. Interested parties can download our notes below. Note that you will need a copy of the original ISO standard in order to use this document.
http://www.pdflib.com/fileadmin/pdflib/pdf/misc/PDFlib-GmbH-notes-on-PDFVT.pdf

PDFlib and PDF/VT

PDF/VT support in PDFlib, PDFlib+PDI and PDFlib Personalization Server (PPS) is based on PDF/X-4 and PDF/X-5 support which has been introduced in 2009. All relevant PDF/X features and requirements in PDFlib apply to PDF/VT as well. This includes color management features with ICC profiles, output intents for characterizing the intended printing condition, and rules regarding the use of color, layers, and transparency in the document. Since PDFlib already supported externally referenced document components for the PDF/X-4p, PDF/X-5g and PDF/X-5pg standards it provided a good basis for the PDF/VT-2 implementation. Similarly, since PDFlib has always supported in-memory document generation and is one of the few products which can interleave PDF creation and output the basis for PDF/VT-2s was also already available. PDFlib supports the creation of documents which conform to PDF/VT-1 and PDF/A at the same time.

PDFlib features for creating PDF/VT-1 and PDF/VT-2 have been added with a focus on automatic creation of unique identifiers and a flexible API for describing document part hierarchy and Document Part Metadata (DPM). Since PDFlib doesn’t know anything about the relationship of multiple documents which have been created separately, scope hints and encapsulation hints can be provided by the application developer. Programming examples for creating PDF/VT are available in the PDFlib Cookbook.

PDF/VT-2s creation can be implemented on top of PDF/VT-1 or PDF/VT-2 by wrapping the PDF/VT documents together with all referenced (external) output intents and PDF contents in a MIME package. The rules for creating standard-conforming PDF/VT-2s MIME packages are described in the PDFlib documentation. Sample code for this task is also available in the PDFlib Cookbook.

Code and PDF Samples for PDF/VT

The PDFlib Cookbook  contains the following code samples for generating PDF/VT documents with PDFlib 9:

The starter_pdfvt1 sample creates a self-contained PDF/VT-1 document;

The starter_pdfvt2 sample creates a PDF/VT-2 file set  with external references to an ICC output intent profile and graphical content, i.e. external PDF documents which include page content that is incorporated by reference;

The starter_pdfvt2s  sample creates a MIME package which conforms to PDF/VT-2s. The package includes several PDF/VT-2 main documents as well as the required dependent files.

The dpart_to_xml sample in the pCOS Cookbook demonstrates how to read and extract Document Part Metadata (DPM) from a PDF/VT document and store it in the XML format specified in the PDF/VT standard.

PDF/VT Resources

ISO 16612-2:2010: Graphic technology — Variable data exchange – Part 2:
Using PDF/X-4 and PDF/X-5 (PDF/VT-1 and PDF/VT-2)
http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=46428

PDF/VT Application Notes by the PDF Association
http://www.pdfa.org/publication/pdfvt-application-notes/

Cal Poly Graphic Communications PDF/VT Test File Suite
http://www.pdfa.org/download/cal-poly-graphic-communications-pdfvt-test-file-suite-version-1-0-1/

Do PDF/VT Right: How to make problem free PDF files for variable data printing
http://www.globalgraphics.com/doPDFVTright/

Adobe PDF Print Engine 3 with support for PDF/VT
http://www.adobe.com/products/pdfprintengine/

PDF Association on PDF/VT
http://www.pdfa.org/competence-centers/pdfvt-competence-center/

PDF Association PDF/VT Icon

International Cooperation for the Integration of Processes in Prepress, Press, and Postpress Organization (CIP4) is the organization responsible for the Job Definition Format (JDF):
http://www.cip4.org/

ICS – Common Metadata for Document Production Workflows
Metadata format recommended for use with PDF/VT
http://www.cip4.org/document_archive/ics.php