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May 2024 by Peter Wyatt (PDF Association)

This article aims to explain the different ways by which PDF stores “files”.

What is meant by a “file” with PDF depends on your viewpoint, and may include notions and expectations derived from how HTML and other formats may do things, some of which differ from the metaphors used by PDF software.

Diverse interfaces foster various end-user understandings of what “files” exist inside any given PDF. This is especially true when we consider the many similar terms in use. Understandings differ or are ambiguous depending on the users’ background, and the terms themselves may have different technical meanings.

Accordingly, end users are sometimes perplexed as to why they cannot simply “download” the JPEG file of a photo in a PDF, or extract a font from PDF viewing software, yet they might be able to extract the embedded spreadsheet they’d attached.

If your role relates to digital preservation or file forensics then accurately understanding the kinds of data that can be in a PDF and how it is stored can be very important.

Integrity protection for encrypted documents: ISO TS 32004 is the latest Extension to PDF 2.0

May 2024 by PDF Association staff (PDF Association)
Announcement, PDF Association news


The latest ISO Extension to PDF 2.0 offers backwards-compatible integrity protection via Message Authentication Code (MAC).

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May 2024 by PDF Association staff (PDF Association)
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The second PDF Week event of 2024 arrives May 6-10 in Tokyo! Members can attend remotely if they cannot join … Read more

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March 2024 by PDF Association staff (PDF Association)
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Authoritative answers to common questions about Tagged PDF, WTPDF and PDF/UA.

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March 2024 by PDF Association staff (PDF Association)
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Join pdfa.org for exclusive member benefits tailored to PDF development. Our Member Benefit Manager, Melina, engages in insightful discussions with … Read more

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March 2024 by PDF Association staff (PDF Association)
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The PDF Association has established a new Liaison Working Group (LWG) to serve as a place for forensics experts and … Read more

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February 2024 by PDF Association staff (PDF Association)
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Well-Tagged PDF (WTPDF), a common specification for both reuse and accessibility, is a massive leap forward for PDF technology.

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February 2024 by PDF Association staff (PDF Association)
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All PDF Association Full and Liaison Members who have joined Technical and/or Liaison Working Groups are welcome for two weeks … Read more

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January 2024 by PDF Association staff (PDF Association)
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Adobe’s Standards Support Endowment, now in its sixth year, facilities administration of ISO TC 171 SC 2 and sustains the … Read more

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January 2024 by Matthias Wagner (PDF Association)
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The PDF Association has updated its website to make content and resources easier to find. We hope you like it!

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November 2023 by PDF Association staff (PDF Association, Inc.)
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The PDF technical community will hold a series of online meetings during February 2024 to continue advancing the PDF file … Read more

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October 2023 by PDF Association staff (PDF Association)
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PDF Week Fall 2023 in San Francisco covered subjects ranging from HDR to compression, color fonts, animation, accessibility and (much!) … Read more

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