PDFA3

PDFA3, short for PDF/A-3, is an ISO standard for the long-term preservation of electronic documents. It is part of the PDF/A family (which also includes PDF/A-1 and PDF/A-2) and is defined as ISO 19005-3. Introduced to extend the archival capabilities of PDF/A, PDF/A-3 allows the inclusion of embedded files within the PDF document itself, enabling archival packages that pair a final document with its original source data or related files.

A core feature of PDF/A-3 is the ability to embed arbitrary file formats inside the PDF, such as the original word processing files, spreadsheets, XML data, or other supporting materials. The standard requires that the document remains self-contained and readable without external dependencies, and it imposes restrictions typical of PDF/A, such as no encryption and the use of fixed metadata and color and font handling to ensure reproducibility over time. Embedded files are stored as attachments and are described through the document’s metadata to aid discoverability and interpretation.

Conformance for PDF/A-3 follows levels similar to earlier parts of PDF/A, with notable forms such as PDF/A-3a (tagged for accessibility) and PDF/A-3b (structural/visual fidelity). The choice of conformance level affects how well the document supports accessibility and how faithfully its appearance is preserved, while still maintaining archival self-containment.

PDFA3 is used by libraries, government agencies, businesses, and archives that require both a readable, stable rendering of documents and a preserved set of associated data or source files. It supports reproducibility and provenance in digital archival workflows, though it can increase file size and requires careful metadata management to ensure embedded content remains interpretable over time.