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

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

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 spec, 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.