PDF files are used in different versions and for different purposes: Not every PDF file is suitable for long-term archiving.

  • Versions: PDF was introduced in version 1.0 in 1993. Version 2.0 has been available since 2017.
  • Variety of use: The purpose of a PDF can be recognized by its attributes. The standards may be combined:

    • PDF/X and VT: prints
    • PDF/A: electronic archiving
    • PDF/E: technical documents / engineering
    • PDF/H: healthcare
    • PDF/UA: accessibility

  • PDF/A: Is generally used for archiving. A distinction must be made between

    • PDF/A-1: suitable for long-term preservation. Recommended for all texts without images. Based on PDF 1.4.
    • PDF/A-2: suitable for long-term preservation. Recommended for all texts with and without images. Based on PDF 1.7.
    • PDF/A-3: any other documents can be embedded in such files. However, with PDF/A-3 long term-preservation is not guaranteed.

  • PDF/A Levels:

    • "b": identical display - usually used for scanned documents or images. In such cases we recommend using PDF/A-2b
    • "u": for scanned texts with OCR.
    • "a": additional access to the content itself. Enables accessibility. Example: "PDF/A-2a". If possible we generally recommend PDF/A-2a for long-term preservation.

  • Conversion: PDFs that do not comply with the PDF/A standard can often (but not always!) be converted to PDF/A. The ZHB uses veraPDF to validate PDFs.
  • Recommendation for long-term preservation: For digital texts, it is best to convert your files to PDF/A-2a. For simple scans of images etc. you may convert them to PDF/A-2b.
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