International standards for HCI and usability
Standards related to usability can be categorised as primarily concerned with:
- the use of the product (effectiveness, efficiency and satisfaction in a particular context of use)
- the user interface and interaction
- the process used to develop the product
- the capability of an organisation to apply user centred design
Figure 1 illustrates the logical relationships: the objective is for the product to be effective, efficient and satisfying when used in the intended contexts. A prerequisite for this is an appropriate interface and interaction. This requires a user centred design process, which to be achieved consistently requires an organisational capability to support user centred design.
The standards described here are divided into these categories, and are listed in the table below.
|Principles and recommendations||Specifications|
|Use in context||ISO/IEC 9126-1: Software Engineering - Product quality - Part 1: Quality model||ISO 20282: Usability of everyday products|
|ISO/IEC TR 9126-4: Software Engineering - Product quality - Part 4: Quality in use metrics|
|ISO 9241-11: Guidance on Usability|
|Interface and interaction||ISO/IEC TR 9126-2: Software Engineering - Product quality - Part 2 External metrics||ISO 9241: Ergonomic requirements for office work with visual display terminals. Parts 3-9|
|ISO/IEC TR 9126-3: Software Engineering - Product quality - Part 3 Internal metrics||ISO/IEC 10741-1: Dialogue interaction - Cursor control for text editing|
|ISO 9241: Ergonomic requirements for office work with visual display terminals. Parts 10-17||ISO/IEC 11581: Icon symbols and functions|
|ISO 11064: Ergonomic design of control centres||ISO 13406: Ergonomic requirements for work with visual displays based on flat panels|
|ISO 14915: Software ergonomics for multimedia user interfaces||ISO/IEC 14754: Pen-based interfaces - Common Gestures for text editing with pen-based systems|
|IEC TR 61997: Guidelines for the user interfaces in multimedia equipment for general purpose use||ISO/IEC 18021: Information Technology - User interface for mobile tools|
|ISO 18789: Ergonomic requirements and measurement techniques for electronic visual displays|
|Documentation||ISO/IEC 18019: Guidelines for the design and preparation of software user documentation||ISO/IEC 15910: Software user documentation process|
|Development process||ISO 13407: Human-centred design processes for interactive systems||ISO/IEC 14598: Information Technology - Evaluation of Software Products|
|ISO TR 16982: Usability methods supporting human centred design|
|Capability||ISO TR 18529: Ergonomics of human-system interaction - Human-centred lifecycle process descriptions|
|Other||ISO 9241-1: Part 1: General Introduction|
|ISO 9241-2: Part 2:Guidance on task requirements|
|ISO 10075-1: Ergonomic principles related to mental workload - General terms and definitions|
|ISO DTS 16071: Guidance on accessibility for human-computer interfaces|
Development of ISO standards
Standards for HCI and usability are developed under the auspices of the International Organisation for Standardisation (ISO) and the International Electrotechnical Commission (IEC). The status of an ISO and IEC documents is summarised in the title of the standard:
|ISO nnnn (date)||A standard number nnnn published on date, developed by an ISO committee.|
|ISO nnnn-xx (date)||Part xx of a standard developed by an ISO committee.|
|ISO/IEC nnnn (date)||A standard developed by JTC1: a joint technical committee of ISO and IEC.|
|ISO TS nnnn (date)||An ISO Technical Specification: a normative document that may later be revised and published as a standard.|
|ISO TR nnnn (date)||An ISO Technical Report: an informative document containing information of a different kind from that normally published in a normative standard.|
|ISO ZZ nnnn (date)||A draft standard of type ZZ made available on date.|
The main stages of development of international standards and abbreviations (ZZ) used for the document types are shown below:
|Stage||Document type||Abbrev. meaning||Description|
|1||AWI||Approved Work Item||Prior to a working draft|
|2||WD||Working Draft||Preliminary draft for discussion by working group|
|3||CD||Committee Draft||Complete draft for vote and technical comment by national bodies|
|CD TR or TS||Committee Draft Technical Report/Specification|
|4||CDV||Committee Draft for Vote (IEC)||Final draft for vote and editorial comment by national bodies|
|DIS||Draft International Standard|
|FCD||Final Committee draft (JTC1)|
|DTR or DTS||Draft Technical Report/Specification|
|5||FDIS||Final Draft International Standard||Intended text for publication for final approval|
|6||ISO||International Standard||Published document|
|ISO TR or TS||Technical Report or Technical Specification|
This standard (which is part of the ISO 9241 series) provides the definition of usability that is used in subsequent related ergonomic standards:
Usability: the 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.
ISO 9241-11 explains how to identify the information that it is necessary to take into account when specifying or evaluating usability in terms of measures of user performance and satisfaction. Guidance is given on how to describe the context of use of the product and the measures of usability in an explicit way. It includes an explanation of how the usability of a product can be specified and evaluated as part of a quality system, for example one that conforms to ISO 9001.
It also explains how measures of user performance and satisfaction can be used to measure how any component of a work system affects the quality of the whole work system in use.
ISO/IEC 9126: Software product evaluation - Quality characteristics and guidelines for their use (1991)
In the software engineering community the term usability has been more narrowly associated with user interface design. ISO/IEC 9126, developed separately as a software engineering standard, defined usability as one relatively independent contribution to software quality associated with the design and evaluation of the user interface and interaction:Usability: a set of attributes that bear on the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users.
ISO/IEC 9126 (1991) has recently been replaced by a new four part standard that has reconciled the two approaches to usability. ISO/IEC 9126-1 describes the same six categories of software quality that are relevant during product development: functionality, reliability, usability, efficiency, maintainability and portability:
The definition of usability is similar:
Usability: the capability of the software product to be understood, learned, used and attractive to the user, when used under specified conditions.
The phrase "when used under specified conditions" (equivalent to "context of use" in ISO 9241-11) was added to make it clear that a product has no intrinsic usability, only a capability to be used in a particular context.
The standard now recognises that usability plays two roles (Bevan 1999): a detailed software design activity (implied by the definition of usability), and an overall goal that the software meets user needs (similar to the ISO 9241-11 concept of usability). ISO/IEC 9126-1 uses the term "quality in use" for this broad objective:
Quality in use: the capability of the software product to enable specified users to achieve specified goals with effectiveness, productivity, safety and satisfaction in specified contexts of use.
Quality in use is the combined effect of the six categories of software quality when the product is in use. The overall objective is to achieve quality in use, both for the end user and the support user. Functionality, reliability, efficiency and usability determine quality in use for an end user in a particular context. The support user is concerned with the quality in use of maintenance and portability tasks.
Other parts of ISO/IEC 9126 define metrics for usability and quality in use.
Use in context
This technical report contains examples of metrics for effectiveness, productivity, safety and satisfaction. Specifying usability requirements and verifying that they have been achieved in a usability test is an important component of user centred design (ISO 13407). ISO/IEC 9126-4 suggests metrics for effectiveness, productivity, satisfaction and safety that can be used for this purpose. The results can be documented using the Common Industry Format for usability test reports, which is included as an example in an Annex to ISO/IEC 9126-4.
A multi-part standard is being developed to specify the information about usability that should be provided with a consumer product, so that a purchaser can judge the ease of use of the product. It will specify a test method, the characteristics of a "normal user", and how to specify the characteristics of intended users with special needs or with special skills or experience (Bevan and Schoeffel, 2001).
Software interface and interaction
These standards can be used to support user interface development in the following ways:
- To specify details of the appearance and behaviour of the user interface. ISO 14915 and IEC 61997 contain recommendations for multi-media interfaces. More specific guidance can be found for icons in ISO/IEC 11581, PDA's in ISO/IEC 18021 and cursor control in ISO/IEC 10741.
- To provide detailed guidance on the design of user interfaces (ISO 9241 parts 12-17).
- To provide criteria for the evaluation of user interfaces (ISO/IEC 9126 parts 2 and 3).
However the attributes that a product requires for usability depend on the nature of the user, task and environment. ISO 9241-11 can be used to help understand the context in which particular attributes may be required. Usable products can be designed by incorporating product features and attributes known to benefit users in particular contexts of use.
ISO 9241 provides requirements and recommendations relating to the attributes of the hardware, software and environment that contribute to usability, and the ergonomic principles underlying them. Parts 10 and 12 to 17 deal specifically with attributes of the software. Parts 14-17 are intended to be used by both designers and evaluators of user interfaces, but the focus is primarily towards the designer.
The standards provide an authoritative source of reference, but designers without usability experience have great difficulty applying these types of guidelines (de Souza and Bevan 1990). To apply guidelines successfully, designers need to understand the design goals and benefits of each guideline, the conditions under which the guideline should be applied, the precise nature of the proposed solution, and any procedure that must be followed to apply the guideline. Parts 12 to 17 contain a daunting 82 pages of guidelines, but even then do not provide all this information for every guideline.
Several checklists have been prepared to help assess conformance of software to the main principles in ISO 9241 (Gediga 1999, Oppermann and Reiterer 1997, Prümper 1999).
Part 10: Dialogue principles (1996)
This part deals with general ergonomic principles which apply to the design of dialogues between humans and information systems: suitability for the task, suitability for learning, suitability for individualisation, conformity with user expectations, self descriptiveness, controllability, and error tolerance.
Part 12: Presentation of information (1998)
This part contains recommendations for presenting and representing information on visual displays. It includes guidance on ways of representing complex information using alphanumeric and graphical/symbolic codes, screen layout, and design as well as the use of windows.
Part 13: User guidance (1998)
This part provides recommendations for the design and evaluation of user guidance attributes of software user interfaces including prompts, feedback, status, on-line help and error management.
Part 14: Menu dialogues (1997)
This part provides recommendations for the design of menus used in user-computer dialogues. The recommendations cover menu structure, navigation, option selection and execution, and menu presentation (by various techniques including windowing, panels, buttons, fields, etc.).
Part 15: Command dialogues (1997)
This part provides recommendations for the design of command languages used in user-computer dialogues. The recommendations cover command language structure and syntax, command representations, input and output considerations, and feedback and help.
Part 16: Direct manipulation dialogues (1999)
This part provides recommendations for the ergonomic design of direct manipulation dialogues, and includes the manipulation of objects, and the design of metaphors, objects and attributes. It covers those aspects of Graphical User Interfaces that are directly manipulated, and not covered by other parts of ISO 9241.
Part 17: Form filling dialogues (1998)
This part provides recommendations for the ergonomic design of form filling dialogues. The recommendations cover form structure and output considerations, input considerations, and form navigation.
ISO/IEC 9126-1 defines usability in terms of understandability, learnability, operability and attractiveness. Parts 2 and 3 include examples of metrics for these characteristics. These can be used to specify and evaluate detailed usability criteria.
Part 2: External metrics (DTR: 2001)
This technical report describes metrics that can be used to specify or evaluate the behaviour of the software when operated by the user. For example: how long does it take to learn to use a function, can users undo functions, do users respond appropriately to error messages?
This technical report describes metrics that can be used to create requirements that that describe static properties of the interface that can be evaluated by inspection without operating the software. For example: what proportion of the functions are documented, what proportion of functions can be undone, what proportion or error messages are self explanatory?
Part 1: Icons - General (2000)
This part contains a framework for the development and design of icons, including general requirements and recommendations applicable to all icons.
Part 2: Object icons (2000)
This part contains requirements and recommendations for icons that represent functions by association with an object, and that can be moved and opened. It also contains specifications for the function and appearance of 20 icons.
Part 3: Pointer icons (2000)
This part contains requirements and recommendations for 8 commonly used pointer icons that represent a pointer associated with a physical input device. It also specifies how pointer icons change appearance to give user feedback.
Part 4: Control icons (CD: 1999)
This part contains requirements and recommendations for 14 commonly used control icons that enable the user to operate on windows, lists and other graphical elements.
Part 5: Tool icons (FCD: 2000)
This part contains requirements and recommendations for 20 commonly used icons for tools, and specifies the relationships between tool and pointer icons
Part 6: Action icons(1999)
This part contains requirements and recommendations for 23 commonly used icons typically used on toolbars that represent actions by association with objects that prompt the user to recall the intended actions.
This standard specifies how the cursor should move on the screen in response to the use of cursor control keys.
This standard contains user interface specifications for PDA's with a data interchange capability with corresponding servers.
Part 1: Design principles and framework (DIS: 2000)
This part provides as an overall introduction to the standard.
Part 2: Multimedia control and navigation (CD: 2000)
This part provides recommendations for navigation structures and aids, media controls, basic controls, media control guidelines for dynamic media and controls and navigation involving multiple media.
Part 3: Media selection and combination (DIS: 2000)
This part provides general guidelines for media selection and combination, media selection for information types, media combination and integration and directing users' attention.
Part 4: Domain specific multimedia interfaces (AWI)
This part is intended to cover computer based training, computer supported co-operative work, kiosk systems, on-line help and testing and evaluation.
IEC CDV TR 61997: Guidelines for the user interfaces in multimedia equipment for general purpose use (2000)
This technical report gives general principles and detailed design guidance for media selection, and for mechanical, graphical and auditory user interfaces.
These standards can be used in the design and evaluation of workplaces, screens, keyboards and other input devices. Unlike the software standards, most of these standards contain explicit requirements. ISO 9241 and ISO 13406 contain requirements for visual display terminals in offices. These standards can be used to support adherence to European regulations for the use of display screens (Bevan 1991).Gestures for pen-based systems are covered in ISO/IEC 14754.ISO 11064 contains ergonomic requirements for the design of control centres.
ISO 9241 provides requirements and recommendations relating to the attributes of the hardware, software and environment that contribute to usability, and the ergonomic principles underlying them. Parts 3 to 9 contain hardware design requirements and guidance.
Part 3: Visual display requirements (1992)
This part specifies the ergonomics requirements for display screens that ensure that they can be read comfortably, safely and efficiently to perform office tasks. Although it deals specifically with displays used in offices, it is appropriate for most applications that require general-purpose displays to be used in an office-like environment.
Part 4: Keyboard requirements (1998)
This part specifies the ergonomics design characteristics of an alphanumeric keyboard that may be used comfortably, safely and efficiently to perform office tasks. Keyboard layouts are dealt with separately in various parts of ISO/IEC 9995: Information Processing - Keyboard Layouts for Text and Office Systems (1994).
Part 5: Workstation layout and postural requirements (1998)
This part specifies the ergonomics requirements for a Visual Display Terminal workplace that will allow the user to adopt a comfortable and efficient posture.
Part 6: Guidance on the work environment (1999)
This part provides guidance on the Visual Display Terminal working environment (including lighting, noise, temperature, vibration and electromagnetic fields) that will provide the user with comfortable, safe and productive working conditions.
Part 7: Requirements for display with reflections (1998)
This part specifies methods of measurement of glare and reflections from the surface of display screens, including those with surface treatments. It is aimed at display manufacturers who wish to ensure that anti-reflection treatments do not detract from image quality.
Part 8: Requirements for displayed colours (1997)
This part specifies the requirements for multicolour displays that are largely in addition to the monochrome requirements in Part 3.
Part 9: Requirements for non-keyboard input devices (2000)
This part specifies the ergonomics requirements for non-keyboard input devices that may be used in conjunction with a visual display terminal. It covers such devices as the mouse, trackball and other pointing devices. It also includes a performance test. It does not address voice input.
Part 1: Introduction (1999)
Part 2: Ergonomic requirements for flat panel displays (2001)
This standard establishes ergonomic image-quality requirements for the design and evaluation of flat panel displays and specifies methods of determining image quality.
ISO AWI 18789: Ergonomic requirements and measurement techniques for electronic visual displays (1999)
This standard is intended to revise and replace ISO 9241 Parts 3, 7 and 8 and ISO 13406.
ISO/IEC 14754: Pen-based interfaces - Common gestures for text editing with pen-based systems (1999)
This standard defines a set of basic gesture commands and feedback for pen interfaces. The gestures include: select, delete, insert space, split line, move, copy, cut, paste, scroll and undo.
This eight part standard contain ergonomic principles, recommendations and guidelines.
Part 1: Principles for the design of control centers (2000) Part 2: Principles of control suite arrangement (2000) Part 3: Control room layout (1999) Part 4: Workstation layout and dimensions (CD: 2000) Part 5: Human-system interfaces (WD: 1999) Part 6: Environmental requirements for control rooms (WD: 2000) Part 7: Principles for the evaluation of control centers (WD: 2000) Part 8: Ergonomic requirements for specific applications (WD: 2000)
ISO/IEC 15910 provides a detailed process for the development of user documentation (paper and on-line help), while ISO/IEC 18019 gives more guidance on how to produce documentation that meets user needs.
ISO/IEC 15910: Software user documentation process (1999)
This standard specifies the minimum process for creating user documentation for software that has a user interface, including printed documentation (e.g. user manuals and quick-reference cards), on-line documentation, help text and on-line documentation systems.
This standard describes how to establish what information users need, how to determine the way in which that information should be presented to the users, and how then to prepare the information and make it available. It covers both on-line and printed documentation and has been developed from two British Standards:
The standard is intended to compliment ISO/IEC 9127 - User documentation and cover information for software packages, and ISO/IEC 15910 Software user documentation process.
The Development Process
ISO 13407 explains the activities required for user centred design, and ISO 16982 outlines the types of methods that can be used. ISO/IEC 14598 give a general framework for the evaluation of software products using the model in ISO/IEC 9126-1.
This standard provides guidance on human-centred design activities throughout the life cycle of interactive computer-based systems. It is a tool for those managing design processes and provides guidance on sources of information and standards relevant to the human-centred approach. It describes human-centred design as a multidisciplinary activity, which incorporates human factors and ergonomics knowledge and techniques with the objective of enhancing effectiveness and efficiency, improving human working conditions, and counteracting possible adverse effects of use on human health, safety and performance.
The EU-funded INUSE project has developed a more detailed procedure and a set of criteria that can be used to assess how closely a development process has followed the principles of ISO 13407. The TRUMP project recommended specific methods for user centred design based on ISO 13407.
This technical report outlines the different types of usability methods that can be used to support user centred design.
This multi-part standard specifies the process to be used to evaluate software products. The first part included the original definition of quality in use.
Capability of the organisation
The usability maturity model in ISO TR 18529 contains a structured set of processes derived from ISO 13407 and a survey of good practice. It can be used to assess the extent to which an organisation is capable of carrying out user-centred design. Each HCD process (such as "specify the user and organisational requirements") can be rated on the ISO 15504 Software Process Assessment scale: Incomplete, Performed, Managed, Established, Predictable or Optimising (Earthy et al, 2001).
This Technical Report contains a structured and formalised list of human-centred processes:
HCD.1 Ensure HCD content in system strategyHCD.2 Plan and manage the HCD process HCD.3 Specify the user and organisational requirements HCD.4 Understand and specify the context of use HCD.5 Produce design solutions HCD.6 Evaluate designs against requirements HCD.7 Introduce and operate the system
The Usability Maturity Model in ISO TR 18529 is based on the model developed by the INUSE project.
Other related standards
This part introduces the multi-part standard ISO 9241 for the ergonomic requirements for the use of visual display terminals for office tasks and explains some of the basic underlying principles. It provides some guidance on how to use the standard and describes how conformance to parts of ISO 9241 should be reported.
This part deals with the design of tasks and jobs involving work with visual display terminals. It provides guidance on how task requirements may be identified and specified within individual organisations and how task requirements can be incorporated into the system design and implementation process.
This part of ISO 10075 explains the terminology and provides definitions in the area of mental workload.
This technical specification (derived from ANSI HFS 200) provides guidelines and recommendations for the design of systems and software that will enable users with disabilities greater accessibility to computer systems (with or without assistive technology). It includes low vision users, hearing impaired users, deaf users, users with physical and cognitive impairments, and the elderly.
Where to get international standards
ISO standards have to be purchased. They can be obtained direct from ISO, or from a national standards body, NSSN: A National Resource for Global Standards also has a comprehensive list of standards, some of which can be purchased as pdf files. In principle draft ISO standards can also be purchased, but while the FDIS and DIS documents published by ISO are easy to obtain, to obtain earlier drafts (e.g. FCD, CD or DTR) the individual secretariats have to be approached. While these early drafts may give a good indication of the likely content of the final standard, they are often subject to major change, and in some cases may never be published.
National standards bodies BSI: British Standards Institute ANSI: American National Standards Institute.
Support for legislation
The European Display Screen Equipment Directive (EEC, 1990) specifies minimum ergonomic requirements for workstation equipment and the environment. These can be achieved by conforming to ISO 9241 parts 3-9. The Directive also requires that the "principles of software ergonomics" are applied in designing the user interface. ISO 9241 part 10 contains appropriate principles. The other requirements for ease of use of software can be met by conforming to ISO 9241 parts 12 -17.
The Machinery Directive (EC, 1998) requires suppliers to provide machinery that meets essential health and safety requirements, one of which is that the interactive software is "user friendly".
The Supplier's Directive (EEC, 1993) requires that the technical specifications used for procurement by public bodies must make reference to relevant standards adopted by the European standards body (CEN). These could include ergonomic and user interface standards, provided that they have explicit conformance requirements.
European Union countries have national legislation to implement these Directives.
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