PDF 2.0 Application Note 002: Associated Files

Associated Files (defined in ISO 32000-2, 14.13) leverage the ubiquity of PDF to build on the commonplace concept of “attachments” in electronic communications.

The Associated Files model is exceptionally flexible and can address a wide variety of use cases. Using the Associated Files feature, PDF 2.0 writers can provide additional information as files related to a PDF object in a standardized and therefore machine-readable and potentially machine-actionable way. The Associated Files mechanism also provides for connecting metadata about a related object with the related object itself.

The Associated Files mechanism was introduced in PDF/A-3 and became part of the PDF specification with PDF 2.0 published in 2017.