This section on PDF/A is part of the Library of Congress website on sustainable formats. The page includes description of PDF/A, sustainability factors, quality and functionality factors, format specifications, and useful references.
PDF/A is a family of ISO standards that attempt provide sustainable formats, through device independence, self-containment, and self-documentation. The PDF/A standards are developed and maintained by a working group with representatives from government, industry, and academia and active support from Adobe Systems Incorporated.
PDF/A-1, the first PDF/A standard, was based on PDF version 1.4 and published in 2005.
PDF/A-2 extends the capabilities of PDF/A-1 and is based on PDF version 1.7.
PDF/A-3 allows including in a PDF/A file, other types of files in any other format, not just other PDF/A files.
Restrictions on PDF/A files include:
- Audio and video content are forbidden
- All fonts must be legally embeddable for unlimited, universal rendering
- Colorspaces specified in a device-independent manner
- Encryption is disallowed
- Use of standards-based metadata is mandated