“[...] a file format based on PDF, called PDF/A, which provides a mechanism to display electronic documents in a way, that their virtual appearance stays reproducable over long periods independent of the tools and systems used for the creation, storage and reproduction of the document." (ISO 19005-1)

Requirements of electronic documents for archiving
The standard is not defining specific archiving strategies and goals. It rather describes the technical and formal requirements of electronic documents ensuring their eligibility for safe long-term archiving.

Embedded information
A key factor to ensure the reproducibility of PDF/A documents is to embed all necessary information into the document itself. This means visible content like text, vector graphics, picture frames, fonts, color spaces and many more.

In addition a PDF/A document must neither directly nor indirectly refer to external sources. An example would be a connection fonts not embedded in the document itself.

Comparison of PDF and PDF/A

PDF/A in the engineering industry