The PDF 2.0 Application Note 002: Associated Files is the second PDF 2.0 Application Note to be published by the PDF Association.
Associated Files (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 open, and can address a wide variety of use cases. Using the Associated Files feature, PDF writers can provide additional information about files related to a PDF file 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.