Facebook
Twitter
YOUTUBE
LINKEDIN
XING
About the contributor
PDF Association

Mission Statement: To promote Open Standards-based electronic document implementations using PDF technology through education, expertise and shared experience for stakeholders worldwide.
More contributions
Interview with René Treuber, Product Manager of axaio software, about PDF Days Europe 2018

René Treuber, Product Manager of axaio software, will be hosting a presentation titled “Introducing ISO standards for PDF “processing steps” and “print product metadata”” at the PDF Days Europe 2018. In this Interview he gives some background information about it.

Interview with Roman Toda, CTO of Normex, about PDF Days Europe 2018

Roman Toda, CTO of Normex, will be hosting a presentation titled “Encryption with PDF 2.0” at the PDF Days Europe 2018. In this interview he gives some background information about it.

PANEL “Five visions of a PDF future” at the PDF Days Europe 2018

Catherine Andersz (PDFTron), Richard Cohn (Adobe), Harald Grumser (Compart), Carsten Heiermann (Foxit) and Duff Johnson (PDF Association) present their ideas for the next 25 years of PDF.

Interview with Dietrich von Seggern, CEO of callas software, about PDF Days Europe 2018

Dietrich von Seggern, CEO of callas software, will be hosting a presentation titled “Text and fonts in PDF” at the PDF Days Europe 2018. In this Interview he gives some background information about it.

Interview with Ulrich Isermeyer, Sr. Business Development Manager, Adobe Systems GmbH, about PDF Days Europe 2018

Ulrich Isermeyer, Sr. Business Development Manager, Adobe Systems GmbH, will be hosting a presentation titled “The power of 3D PDF” at the PDF Days Europe 2018. In this Interview he gives some background information about it.

The technical side of the PDF/A standard


After the first part of PDF/A was published, two more parts arrived. These are not replacements for part 1, however; rather, they offer additional options for archiving PDF documents. All existing PDF/A files remain fully valid.

PDF/A-1: The first archiving standard

PDF/A-1 is based on PDF version 1.4, which first appeared in 2001. All resources (images, graphics, typographic characters) must be embedded within the PDF/A document itself. A PDF/A file requires precise, platform-independent colour data using ICC profiles, and XMP for the document metadata. Transparent elements, some forms of compression (LZW, JPEG2000), PDF layers, and certain actions or JavaScript are forbidden. A PDF/A file must not be password-protected. PDF/A-1 expressly supports embedded digital signatures and the use of hyperlinks.

PDF/A-2: Based on PDF 1.7

PDF/A-2 was published in 2011 as “ISO 19005-2”. Based on PDF version 1.7, which has since been standardised as “ISO 32000-1”, it makes use of this version’s new features. This means PDF/A-2 allows JPEG2000 compression, transparent elements and PDF layers. PDF/A-2 also allows you to embed OpenType fonts and supports PAdES (PDF Advanced Electronic Signatures)-compliant digital signatures. One particularly important innovation is the “container” function: PDF/A files can be embedded within a PDF/A-2 document.

PDF/A-3: One more feature

PDF/A-3 has been available since October 2012. A PDF/A-3 document allows you to embed any file format desired – not just PDF/A documents. For example, a PDF/A-3 file can contain the original file from which it was generated. The PDF/A standard does not regulate the suitability of these embedded files for archiving.

Conformance levels: A, B, U

The different conformance levels reflect the quality of the archived document and depend on the input material and the document’s purpose.

  • Level A (Accessible) meets all requirements for the standard, including the logical structure of the document and its correct reading order. Text must be extractable and the logical structure must match the natural reading order. Fonts used must meet stringent requirements. This PDF/A level can usually only be met by converting born-digital documents.
  • Level B (Basic) guarantees that the content of the document can be unambiguously reproduced. Level B files are easier to create than Level A, but Level B does not guarantee 100% text extraction or searchability. It does not necessarily mean that the content can be reused without any problems. Scanned paper documents can usually be converted to PDF/A Conformance Level B without any extra work.
  • Level U (Unicode) was introduced along with PDF/A-2. It expands Conformance Level B to specify that all text can be mapped to standard Unicode character codes.

Nomenclature: PDF/A versions and levels are simply given one after another. A PDF/A-1b file, for example, is a PDF file for long-term archiving, of the first generation, with visually reproducible content.

< previousoverviewnext >


Tags: Conformance levels, ISO Standard
Categories: PDF, PDF/A