MBUI - Glossary

W3C Working Group Note 07 January 2014

This version:
Latest version:
Jaroslav Pullmann, Fraunhofer FIT


This document is a glossary of terms recurrent in the Model-based User Interface domain (MBUI). It is intended to capture a common, coherent terminology for specifications of the MBUI Working Group and to provide a concise reference of domain terms for interested audience. The document arose from a thorough review and discussion of the glossaries published by the CAMELEON and AMODEUS research projects.

Status of This Document

This document was published by the MBUI working group and defines a glossary of terms for use within specifications of the MBUI Working Group.If you wish to make comments regarding this document, please send them to public-mbui@w3.org (subscribe, archives). All comments are welcome.

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

Publication as a Working Group Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Table of Contents

  1. Definitions
  2. Acknowledgements


Abstract Interaction Object (AIO)

W3C recommended term: Abstract Interaction Unit.

Abstract Interaction Unit (AIU)

(a) Interaction unit that is independent from the interaction modalities and from the implementation technology.

(b) Component of an Abstract User Interface (AUI).

Synonyms: Abstract interactor, Abstract Interaction Object, Presentation Unit.

Abstract interactor

W3C recommended term: Abstract Interaction Unit.

Abstract task

Composite task whose subtasks categories are different (i.e. a mix of any of the following: user task, system task, interaction task and abstract task).

Abstract User Interface (AUI)

(a) Composition of Abstract Interaction Units along with their abstract behaviour.

(b) Metonymic use for Abstract User Interface model.


Transformation of a model into a different model whose semantic content and scope are higher than the content and scope of the original model.

Comment: opposite of Concretization.


Ability of a UI to adapt as a result of an explicit human intervention according to a set of predefined options.

Synonyms: Customizability.

Adaptable User Interface (Adaptable UI)

UI that supports Adaptability.

Adaptive User Interface (Adaptive UI)

UI that supports Adaptivity.


Ability of a UI to adapt itself without any explicit human intervention.

Application task

W3C recommended term: System task.

Articulatory task

Task that modifies the state of the user interface without modifying the domain-dependent state. Examples are: "scroll", "zoom", "page navigation".


The ability of the interactive system to provide articulatory tasks to make observable the system state that is relevant in the current situation.

Central domain concept

Domain-dependent concept whose relevance for the user is key (to accomplish a particular task - or a set of tasks, in a particular context of use - or set of contexts of use). It should be directly observable.

Composite Task

Task that can be decomposed into sub-tasks.


Opposite of Abstraction.

Concrete Interaction Object (CIO)

W3C recommended term: Concrete Interaction Unit.

Concrete Interaction Unit (CIU)

(a) Interaction unit that is defined in terms of some interaction modality and independently from any implementation technology.

(b) Component of a Concrete User Interface (CUI). Examples include: Radio button, drop-down menu, input field

Synonyms: Concrete interactor, Concrete Interaction Object.

Concrete Interactor

W3C recommended term: Concrete Interaction Unit.

Concrete User Interface (Concrete UI)

(a) Composition of Concrete Interaction Units along with their concrete behaviour.

(b) Metonymic use for Concrete User Interface model.


In the area of user interface design and development, metonymic use for Context of use.

Context aware UI

User interface that supports context awareness.

Context awareness

Ability of an interactive system to detect (changes in) the context of use and to identify changes that are relevant.

Context of use

Relevant information used at design time and/or at run time about the following:

(1) the user (or set of users) who is (are) intended to use, or is actually using, the interactive system (e.g., capabilities/functional limitations, preferences/needs, profile, idiosyncrasies, current tasks and activities, role);

(2) the platform to be used or is actually used;

(3) the social and physical environment (or set of environments) when/where the interaction will take place, or is actually taking place. This includes numeric and/or symbolic times and locations (e.g., in the morning, at 4 o'clock, at home, in a public space, on the move in the street, in the train or car), social rules and activities, light, temperature, sound, etc., conditions.

Context sensitive UI

Context aware UI that is able to react to changes of the context of use.


Transformation of a model into another model at a different level of abstraction (higher or lower), while changing the context of use.


W3C recommended term: Adaptability.


An apparatus incorporating, or managing, a collection of peripherals, and which appears to a user as a functional unit through which to perform an interaction process. A device can include computational abilities, act as a stand-alone interactive system, or be part of a network. Examples include iPhone 4, Samsung Galaxy III, MS Kinect, Wii...

Distribution (of the User Interface)

Allocation of user interface components across devices. The granularity for distribution may be one of (in decreasing order): application level (e.g., full replication of the UI on different devices), Abstract Interaction Unit level, domain concept level, or even portions of Concrete Interaction Units.

Distributed User Interface (Distributed UI)

Distributed user interfaces allow access to an application through multiple devices at a given time.


The field of interest with respect to which an interactive application is developed.

Synonyms: Application domain.

Domain concept

Concept relevant to users to accomplish tasks in a particular application area.

Synonyms: Domain object.

Domain model

Set of domain concepts and their relationships.

Domain object

W3C recommended term: Domain concept

Elementary device

Device that cannot be decomposed, i.e. if it were decomposed, it would not function as a computational unit anymore. Examples include personal computers, tablets, or mobile phones.

Elementary task

Task that is not decomposed into subtasks.

Entry point

Any level of abstraction in the transformation process from which the development of a UI is initiated.


Metonymic use for physical and social environment.

Executable User Interface

W3C recommended term: Final User Interface.

Final User Interface

(a) Source code of a UI, in any programming language or markup language (e.g., Java, HTML5, VoiceXML) that can be interpreted or executed.

(b) Metonymic use for FUI model.

Synonyms: Executable User Interface.

Forward engineering.

Process of developing a software product. The opposite of reverse engineering.


Process by which two or more systems are coupled so that they reciprocally influence each other's state or behaviour. When at least one of the systems is a human being, and one is a computational system we speak of Human-Computer Interaction.

Interaction device

Synonyms: Interaction resource, physical device.

Interaction language

Language used by the user or the system for interacting. A language defines the set of all possible well-formed expressions, i.e. the conventional assembly of symbols, that convey meaning.

Interaction modality

(a) Type of communication channel to acquire (input modality) or convey information (output modality) in an interaction between a user and an interactive system.

(b) Coupling of an interaction device peripheral with an interaction language.

Comment: the couple <pen, pseudo-natural language> and <keyboard, pseudo-natural language> are two interaction modalities (they use the same interaction language but two distinct input devices peripherals).

Interaction resource

Interaction device used by the user to manipulate and/or observe the state of an interactive system. Examples include screens, keyboard, mouse, real world objects (such as phicons).

Interaction space

A collection of interactors that support the execution of a set of logically/semantically connected tasks. In graphical user interfaces, an interaction space can be mapped onto a window, a set of panels, or generally a container of some sort.

Synonyms: Workspace, presentation unit

Interaction task

Task performed by the user to modify and/or observe the state of the interactive system (e.g., editing, selecting from an item list, filtering, scrolling and zooming).

Interaction unit

An entity that supports a task or a set of sub-tasks that are logically related to achieve a goal (or a set of goals).

Interactive system

A computational system that supports a set of tasks with the participation of one or more humans by the way of interactions between this system and these humans.


An element of a user interface that embodies particular interaction semantics (e.g.text input, single choice) or functionality (e.g. grouping, navigation). It allows users to observe and/or manipulate domain concepts and functions by means of interaction resources. Depending on the level of abstraction an interactor might specify a concrete appearance.

Level of abstraction

(a) Layer within a system whose information types are characterized by a given semantic content and scope. The lowest level of abstraction corresponds to the poorest information type with regard to scope and content. The highest level of abstraction corresponds to the richest information type with regard to scope and content. These levels as well as any level in-between depend on the perspective or the objective of the modeler and/or the modeling technique.

(b) Different perspectives in the development process of a system.


Correspondence between elements of a source model and elements of a target model. For example, for traceability purpose, the correspondence between a source task and its target AIU(s) can be maintained as a mapping function.


Model that sets the rules and the constraints for producing the construction of models. As such, it is defines a set of models that comply with it.

Comment: a model complies to a single meta-model, whereas a meta-model may have many compliant models.

Migration (of a User Interface)

Transfer of all, or parts, of the user interface between different devices. May occur at run time or between sessions.

Migratory User Interface (Migratory UI)

Migratory user interfaces can move to a different device while preserving their state across the devices involved.


(a) Metonymic use for interaction modality.

(b) Can be perceived by one of the human perceptual senses.


Any representation of a real or imagined system or entity for a particular purpose. In the context of MBUID, a model is any representation of a real or imagined aspect of an interactive software for the purpose of user interface development.

Multi-device User Interface (Multi-device UI)

Multi-device user interfaces can be accessed through multiple devices.

Comment: this is a general category, which includes various non-exclusive subcases, such as distributed UIs, migratory UIs, and still others. There are user interfaces that are both distributed and migratory, others that belong to only one of these two categories, and others that are neither distributed nor migratory (e.g. responsive design).

Multi-modal User Interface (Multi-modal UI)

UI that supports multi-modality.

Multi-modality (of a User Interface)

Capability of an interactive system to support multi-modal interaction, i.e., the user is provided with more than one modality (simultaneously or not) to observe the system state and/or can use more than one modality (simultaneously or not) to communicate information to the system.


Multiple contexts of use considered at design time for UI development.

Multi-target User Interface (Multi-target UI)

User interface that supports multiple targets (i.e., multiple types of users, platforms and environments).

Nomadic application

Interactive system that supports mobile users.


Ability of the interactive system to make perceivable the system state that is relevant in the current situation.

Comment: central domain concepts should be observable. If this is not possible (due to insufficient interaction resources), then they should be browsable.


A physical or virtual component of an interactive system through which input and/or output occur. Depending on its role, a peripheral can be a sensor or an effector. Examples include actual or virtual keyboard, loudspeaker, pen, mouse, motion sensors. A peripheral is usually embodied into, or connected with, a device, which is responsible for its management.

Physical and social environment

Physical and social setting where the interaction takes place or will take place effectively. It is the set of objects, persons and events that are peripheral to the current activity but that may have an impact on the system and/or users behaviour. Examples of environmental dimensions are physical conditions (lighting, surrounding noise, time, location), social conditions (stress, group dynamics, private ou public spaces), and organizational conditions (hierarchy, user's role).

Synonyms: Environment.

Physical and social environment model

Description of the Physical and social environment.

Synonyms: Environment model.

Plastic User Interface (Plastic UI)

User interface that supports plasticity.


Ability of a UI to adapt to different contexts of use while preserving worth for users.


An integrated collection of software and/or hardware technologies and/or resource specifications, which defines specific constraints on, and possibly supports, the implementation of an interactive system and/or of devices for interacting with it. Examples are the Smartphone, Android Smartphone, the Tablet, the Desktop...


Ability of a system to run on systems defined under different platforms without modifying the source code of this system.


(a) Information provided by the user interface at a given time.

(b) Process of rendering information.


Property that allows that some state or set of states can be reached from a given state through user's physical actions on interaction with the system.


Operation that transforms a model into another one at the same level of abstraction for the same context of use.


W3C recommended term: Concretization.

Representation multiplicity (of a domain concept)

Ability of the system to offer alternative representations for a domain concept.

Reverse engineering.

(a) Analysis of a software system so that the software is more understandable for maintenance, evolution, and re-engineering purposes.

(b) Analysis of a system to identify its components and their dependencies to extract and create system abstractions and design information. The original system is not altered. However, additional knowledge about the system is produced. Opposite of forward engineering.

Robustness (of the User Interface)

Ability of the UI to prevent users and system errors, as well as the ability of the UI to increase the chance of successful task accomplishment.

Session Management

Users tend to follow various tasks in parallel. Whereas some tasks can be accomplished in short term, long term tasks might be interrupted by more important ones and continued later on. A session management allows handling of interruptions and the possibility to continue tasks later on.

System Task

Task executed on behalf of the system (e.g., computation of the results of a query).

Synonyms: Application task.


Metonymic use for Context of use at design time.

Target platform

Archetypal platform envisioned for the interactive system.


Activity that should be performed in order to reach a goal.

Task category

Definition of how the performance of the task is allocated. Task category can be user, system, interactive, abstract.

Task model

Description of a set of tasks and their relationships. Relationships can be defined in terms of a hierarchical decomposition of a task into subtasks at different levels of abstraction, or of temporal/causal dependencies/conflicts among subtasks at the same level of abstraction.

Task operator

Operator that denotes temporal relationships among the executions of tasks.

Task presentation set

Set of tasks supported by one presentation.

Task type

Indication of the semantic effect obtained by the performance of a task (e.g. selection, show information, etc.).

Technological space

Community and technology contexts characterized by specific software languages, software technologies, software development methods, knowledge and skills.

Comment: examples include documentware concerned with digital documents expressed in XML, the Java world.


In the context of Model Driven Engineering, production of a set of target models from a set of source models, according to a transformation definition. A transformation definition is a set of transformation rules that together describe how source models are transformed into target models. A set of transformation rules is a model (a transformation model) that complies with a transformation meta-model.


Operation that transforms a model intended for a particular context of use into a model at the same level of abstraction but aimed at a different context of use.

User Interface (UI)

Software components of an interactive system that allow users to observe and manipulate domain-dependent concepts.


Extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.

Usage cost (of an interactor)

Measure of the system resources as well as the human resources the interactor requires.


A human interacting with the interactive system under study.

User task

Task performed by the user without acting on the interactive system explicitly (i.e., an internal cognitive activity, such as selecting a strategy to solve a problem).


W3C recommended term: Abstract Interaction Unit.


We acknowledge the contributions of the members of the W3C MBUI Working Group:

Paolo Bottoni, University of Rome
Heiko Braun, Red Hat
Gaëlle Calvary, University of Grenoble
Joelle Coutaz, University of Grenoble
Gerrit Meixner, Heilbronn University
Vivian Motti, Université catholique de Louvain
Fabio Paternò, Consiglio Nazionale delle Ricerche
Dave Raggett, W3C
Lucio Davide Spano, Consiglio Nazionale delle Ricerche
Jean Vanderdonckt, Université catholique de Louvain