PDF/A and PDF/X standards are defined by the International Organization for Standardization (ISO).

PDF/A standards apply to long-term archiving of electronic documents. The most widely used standards for PDF archiving are PDF/A-1a and PDF/A-1b (for less stringent requirements).
PDF/X standards apply to graphic content exchange. The most widely used standards for a print publishing workflow are several PDF/X formats: PDF/X-1a, PDF/X-3, and PDF/X-4.

For more information on PDF/X and PDF/A, see the ISO website.

This section provides information about the following:

PDF/A
PDF/X

PDF/A

Level A conforming files shall adhere to all of the requirements of the ISO 19005-1:2005 specification.

PDF/A

PDF/A is a file format based on PDF. It provides a mechanism for representing electronic documents in a manner that preserves their visual appearance over time, independent of the tools and systems used for creating, storing, or rendering the files.

PDF/A-1a

A file meeting this conformance level is said to be a "conforming PDF/A -1a file."

PDF/A-1b

In recognition of the varying preservation needs of the diverse user communities making use of PDF files, the ISO 19005-1:2005 specification defines a Level B conformance level. Level B conforming files shall adhere to all of the requirements of the specification except those applicable to Level A only.

A file meeting this conformance level is said to be a "conforming PDF/A-1b file."

The Level B conformance requirements are intended to be those minimally necessary to ensure that the rendered visual appearance of a conforming file is preservable over the long term. However, Level B conforming files might not have sufficiently rich internal information to allow for the preservation of the document's logical structure and content text stream in natural reading order, which is provided by Level A conformance. The requirements for Level A conformance place greater responsibilities on writers of conforming files and those preparing such files, but these requirements allow for a higher level of document preservation service and confidence.

PDF/X

PDF/X is a PDF based format for the exchange of object-based data where individual objects may be in either vector or raster data structures. PDF/X defines a data format and its usage to permit the predictable dissemination of a compound entity to one or more locations, as color-managed, CMYK, gray, RGB, and/or spot color data, in a form ready for final print reproduction, by transfer of a single file. This file contains all the content information necessary to process and render the document, as intended by the sender, coded inside a single PDF file. No other parts, either external files nor internally embedded files, are required or permitted. This exchange requires no prior knowledge of the sending and receiving environments and is sometimes referred to as "blindi" exchange. It is platform- and transport-independent.

PDF/X-3:2003 conforming files shall adhere to all of the requirements of the ISO 15930-6:2003 specification defining "Prepress digital data exchange using PDF -- Part 6: Complete exchange of printing data suitable for colour-managed workflows using PDF 1.4 (PDF/X-3)."

A file meeting this conformance level is said to be a "conforming PDF/X-3 file."