The PDF/UA (PDF/Universal Accessibility) format is a subset of
PDF designed to store any electronic documents in order that they be accessible to people utilizing assistive technologies. The PDF/UA specifications primarily target people with disabilities, such as the blind using text-to-speech screen readers. The PDF/UA format is developed, supported, and standardized by AIIM (Association for Information and Image Management). In 2007 the International Organization for Standardization commenced PDF/UA review as an ISO standard.
See also:
PDF/A,
PDF/E,
PDF/X.