PDF/A

PDF/A is the ISO 19005 profile built for long-term archiving. The goal is simple: a document opened in fifty years should render exactly as it does today, with no missing fonts and no dependence on external resources that may have vanished. To guarantee that, the standard bans anything that could break over time.

In practice a PDF/A file must embed every font it uses, describe colour in a device-independent way (usually an ICC profile), and avoid encryption, JavaScript and links to outside content. All the information needed to reproduce the page has to live inside the file itself. There are conformance levels, from PDF/A-1b (faithful visual reproduction) up to PDF/A-3 (which can carry attached source files), and several parts published over the years.

Archives, courts, libraries and many public administrations require PDF/A precisely because it is self-contained and verifiable. When you prepare a document for the record, the privacy upside is the same as the technical one: a self-contained file processed on your own machine has no hidden dependencies and no copy sitting on someone else's server.