The PDF/UA framework allows assistive technology, PDF applications and the PDF file format to work together optimally so that as many people as possible have access to PDF documents with sound technical support. Disabled users will see the most significant benefits, as they often use a range of assistive technologies to help them access digital content which their disability would otherwise render inaccessible.
Visual or motor impairments
For example, partially-sighted users, depending on the degree of their impairment, may use a larger screen, customised colour and text size settings, or an intelligent screen magnifier. Blind users, or those with particularly severe visual impairments, may use a so-called screen reader (using text-to-speech) and/or a Braille display in order to read PDF documents. A screen reader is a program installed on the user’s computer which reads all visible content aloud. A Braille display is a haptic interface for the same content; it outputs text using raised, moving Braille dots.
A user with restricted arm or hand mobility may use a range of assistive technology to navigate and make use of a PDF document. Instead of a classical computer mouse, they may use a specialist mouse or keyboard, or an onscreen keyboard. Depending on the degree and nature of their disability and their own aptitude, the user may also have other input options, such as special sensors, switches and/or key combinations, or enlargement options. The user can also give spoken commands to speech recognition software or use eye movements and a gaze-tracking system to control their computer.
Reading and writing difficulties
Dyslexic users find it unusually difficult to learn to read. They find it difficult to recognise and process written text. Assistive technologies such as specialised screen readers can help them overcome this. These read content aloud and highlight the same section of text on the screen. This gives the reader a cue, facilitates comprehension and helps them to improve their reading skills and master written language.
Easier reading and navigation on mobile devices
PDF/UA specifies the technical requirements for assistive technology to fully interact with PDF documents using PDF/UA-compliant PDF software. As long as the assistive technology and PDF software used is fully compliant with the standard, the result for disabled users is a high-quality reading and navigational experience. The standard will also benefit other users, however; anyone who reads documents on mobile devices, for example, will appreciate PDF content automatically adjusting itself to a reader-friendly size without affecting the semantic structure.