Functional accessibility

The degree to which a device or interface is usable by a specific user or user profile, either directly or through the addition of assistive technology. A system is functionally accessible for a given user if it enables them to complete their tasks, regardless of whether the underlying architecture was designed with accessibility in mind. The term is used in contrast to intrinsic accessibility: a device may be functionally accessible for blind users through a screen reader bolt-on, but the range of supported users remains limited if the underlying interface only exposes visual metaphors. Functional accessibility is necessarily scoped to particular user profiles and particular assistive technology configurations, whereas intrinsic accessibility aims to support a broad range of users through architectural adaptability.