PDFs are available in different versions and used for different purposes; not every PDF is suitable for long-term preservation.

  • Versions: PDFs were first introduced in 1993 in Version 1.0. Version 2.0 was released in 2017.
  • Range of applications: Different PDF subsets are used for different purposes. The standards can be combined with each other.
    • PDF/X and VT: Used in the printing industry
    • PDF/A: Electronic archiving
    • PDF/E: Technical documents/engineering
    • PDF/H: Health care
    • PDF/UA: Accessibility
  • PDF/A: Generally used for archiving. PDF/A consists of the following subcategories:
    • PDF/A-1: Suitable for long-term preservation. Recommended for all documents without images. Based on PDF 1.4.
    • PDF/A-2: Suitable for long-term preservation. Recommended for all texts with or without images. Based on PDF 1.7.
    • PDF/A-3: Allows embedding of arbitrary additional files. However, standard long-term preservation is not guaranteed.
  • PDF/A Levels:
    • b: Identical representation. Generally used for scanned documents or images. It's best to use PDF/A-2b in this case.
    • u: For scanned texts with OCR.
    • a: Additional access to the content itself. Guaranteed access to the file as text. Enables accessibility. E.g.: PDF/A-2a
  • Conversion: PDFs that do not comply with the PDF/A standard can often (but not always) be converted into PDF/A using the right software. The ZHB uses veraPDF to validate PDFs.
  • We recommend PDF/A-2a as the best file format for all texts produced digitally. For simple scans of images, etc., we recommend PDF/A-2b.
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