What is PDF/A?
PDF/A is a file format for long term archiving of digital documents. This format was standardized by the International Organization for Standardization (ISO) as a subset of the Portable Document Format (PDF).
What is the use of PDF/A?
PDF/A ensures that digital documents are readable, presentable and useable in the long run.
What is the relationship between PDF/A and PDF/UA?
PDF/A is available in several conformity levels: level a (accessible), b (basic), u (unicode). Level a is the highest level. It contains the other levels and requires the availability of tags.
Relationship between PDF/A-a (a = accessible) and PDF/UA. PDF/A-b and PDF/A-u do not require a tag structure.