Mercator

A research screen reader system developed at the Georgia Institute of Technology by W. Keith Edwards and Elizabeth Mynatt for the X Window System on Unix workstations. Mercator pioneered the approach of providing access to graphical user interfaces at the semantic level — translating application operations and affordances into non-visual presentations — rather than simply reading screen contents at the pixel or widget level. The system modeled interfaces as hierarchical tree structures navigable via keyboard, used auditory icons and speech to convey interface objects, and supported speech recognition input. Mercator's proposed modifications to the X Window System's Xt and Xlib libraries were adopted into the X11R6 standard, establishing an early precedent for building accessibility hooks into platform infrastructure.