Glossary

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UAAG(also: User Agent Accessibility Guidelines)

A set of guidelines from the W3C Web Accessibility Initiative that explains how to make user agents — browsers, media players, and other applications that render web content — accessible to people with disabilities. UAAG addresses how user agents should support assistive…

UI Agent(also: User Interface Agent, Browser Agent, AI Agent)

An AI-powered software system that can autonomously interact with graphical user interfaces on behalf of a user, performing tasks by interpreting natural language commands and translating them into interface actions such as clicking buttons, entering text, and navigating between…

Ubiquitous Accessibility(also: Accessibility Everywhere)

A vision for accessibility in which individuals can invoke their needed assistive technologies or access features on any computing device they encounter, rather than being limited to personally owned and configured equipment. As computing becomes embedded in public spaces,…

Ultra-Wideband(also: UWB, Ultra wideband)

A short-range radio-frequency technology that uses very wide frequency bands (typically above 500 MHz) and very short pulses to enable centimetre-accurate distance and angle-of-arrival measurements between paired devices. UWB is increasingly used in accessibility for indoor…

Ultrasonic Sensor(also: Ultrasound Sensor, Proximity Sensor)

A device that measures distance to objects by emitting high-frequency sound waves and calculating the time it takes for the echo to return. In assistive technology, ultrasonic sensors are commonly used in electronic travel aids and wearable navigation devices for blind and…

Unaided AAC(also: Unaided Augmentative and Alternative Communication, Body-Based AAC)

The branch of Augmentative and Alternative Communication that relies solely on the user's body — gestures, facial expressions, vocalisations, manual signs, body orientation — without an external device. Unaided AAC is fast, always available, and naturally expressive; families,…

Unimodal Interface(also: Single-Mode Interface)

An interface that accepts input through only one mode or channel of interaction, such as keyboard-only, voice-only, or gesture-only input. In contrast to multimodal interfaces that combine multiple input methods, unimodal interfaces rely on a single input modality for command…

Unistroke Gesture(also: Single-Stroke Gesture, Unistroke)

A unistroke gesture is a shape or symbol drawn in a single continuous stroke on a touch screen or digitizer, which is then recognized by software as a specific command or input. In accessible interfaces for blind users, unistroke gestures provide an efficient way to create…

Unit Selection Synthesis(also: Concatenative Unit Selection, Unit Selection TTS)

A text-to-speech synthesis approach that generates speech by selecting and concatenating variable-length segments of pre-recorded human speech from a large database to match the input text. Unit selection synthesizers generally produce more natural-sounding speech than…

Universal Maths Conversion Library(also: UMCL)

An open-source programming library that encapsulates converters for different Braille mathematical codes, enabling applications to convert between MathML and various national Braille mathematical notations. UMCL supports multiple Braille math systems including Nemeth code (used…

Universal Remote Console(also: URC, URC Framework)

The Universal Remote Console (URC) is an ISO/IEC standard framework (ISO/IEC 24752) that enables pluggable, alternative user interfaces for applications and devices. URC separates the user interface from the underlying application through an abstract "user interface socket" that…

Universe of One(also: Universe-of-One, Personalized Prompting)

A design approach in assistive technology where content, prompts, and guidance are tailored to each individual user rather than providing generic or standardized instructions. The concept is particularly important for people with cognitive impairments, who often struggle with…

Unobtrusive Interaction(also: Unobtrusive Interfaces)

A design orientation, associated with ambient, wearable, and assistive-technology research, that aims to minimise disruption to users' natural behaviour, attention, and social presence. Rather than demanding foreground engagement (pulling up a phone, pressing through menus,…

Upper-Limb Prosthetic(also: Upper Limb Prosthesis, Arm Prosthetic, Hand Prosthetic)

A prosthetic device that replaces or augments part or all of a missing upper limb — fingers, hand, wrist, forearm, or full arm. Upper-limb prosthetics range from passive cosmetic devices and body-powered cable-driven hands to externally powered myoelectric systems that read…

User Agent(also: Browser, Web Browser)

In web accessibility, a user agent is any software that retrieves, renders, and facilitates user interaction with web content. This includes mainstream web browsers like Chrome, Firefox, and Safari, as well as assistive technologies such as screen readers that work alongside…

User Interface Agent(also: Interface Agent, Software Agent, Assistant Agent)

A software component that observes user behaviour and the state of an application, then unobtrusively offers help — suggestions, shortcuts, summaries, or warnings — to reduce workload or prevent errors. In accessibility research, interface agents have been used to monitor a…

User model(also: User modeling, User modelling)

A computational representation of a user's characteristics, abilities, preferences, and behavior patterns, used to predict how they will interact with a system or to adapt an interface to their needs. In accessibility contexts, user models capture attributes such as motor range…

User profile(also: User model, Personal needs and preferences profile, PNP)

A structured collection of data describing a user's characteristics, capabilities, preferences, and requirements for interacting with a computing system. In accessibility, user profiles inform how interfaces should adapt to meet individual needs. Traditional approaches (such as…

Utterance-Based System(also: Utterance-Based AAC, Prestored Message System)

A type of augmentative and alternative communication (AAC) system that uses prestored phrases, sentences, or complete utterances rather than requiring users to construct messages word-by-word or letter-by-letter. Utterance-based systems organise prestored text hierarchically,…

19 results.