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PDF Association

Mission Statement: To promote Open Standards-based electronic document implementations using PDF technology through education, expertise and shared experience for stakeholders worldwide.
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The Power of the Page

It’s a question that vexes vendors of web-based solutions everywhere: why do people still insist on PDF files? And why does PDF’s mindshare keep going up? “PDF is such antediluvian technology!” they say. “It’s pre-web, are you kidding me? It’s so old-f …

PDF Association technical resources: an overview

PDF is PDF because files produced with one vendor’s software can be read using a different vendor’s software with no loss of fidelity. Interoperability is key to our industry. The PDF Association is a international membership organization dedicated to …

2022: The last year of paper for records-keeping

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PDF 2.0 examples now available

The PDF Association is proud to present the first PDF 2.0 example files made available to the public. Created and donated to the PDF Association by Datalogics, this initial set of PDF 2.0 examples were crafted by hand and intentionally made simple in construction to serve as teaching tools for learning PDF file structure and syntax.

PDF 2.0 interops help vendors

The PDF 2.0 interop workshops included many vendors with products for creating, editing and processing PDF files. They came together in Boston, Massachusetts for a couple of days to test their own software against 3rd party files.

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.

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