ISO/IEC DIS 22121-1.2:2025(en)

ISO/IEC JTC 1/SC 35

Secretariat: AFNOR

Date: 2025-10-11

Information technology — Virtual keyboards user interfaces — Part 1: General guidance and requirements

Technologies de l'information — Interface utilisateur des claviers virtuels — Partie 1 : Directives générales et recommandations

© ISO/IEC 2025, Published in Switzerland

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Contents

Information technology — Virtual keyboards user interfaces — Part 1: General guidelines and recommendations 1

Foreword iv

Introduction iv

1. Scope 1

2. Normative references 1

3. Terms and definitions 1

4. Conformance with ISO/IEC 22121-1 3

5. Virtual keyboards overview 4

5.1. Virtual keyboard displays 4

5.2. Virtual keyboard manipulations 6

5.3. Virtual keyboard contents and outputs 8

6. Virtual keyboards adaptation 9

6.1. Adapted virtual keyboards for specific users 9

6.2. Adapted virtual keyboards for specific technical contexts 9

6.3. Adapted virtual keyboards for specific tasks 10

6.4. Adapted virtual keyboards for specific contexts of use 10

7. Basic functionalities requirements 10

7.1. Visual displays of either the character or symbol keys 10

7.2. Visual feedbacks of the pressed key 11

7.3. Visual enhancements 11

7.4. Audio rendering of either the character or symbol keys 12

8. Advanced functionalities recommendations 13

8.1. Prediction function 13

8.2. Customization of the keyboard 13

Bibliography 14

Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or www.iec.ch/members_experts/refdocs).

ISO and IEC draw attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be held responsible for identifying any or all such patent rights.

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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.

This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 35, User interfaces.

A list of all parts in the ISO/IEC 22121 series can be found on the ISO and IEC websites.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html and www.iec.ch/national-committees.

Introduction

Virtual keyboards are spreading exponentially; with the rise of tactile mobile phones and devices, most users in the world will have to use such interfaces for communication, work or leisure.

Virtual keyboards are mainly designed for text input but can offer various additional functionalities such as navigation, text prediction or gaming.

Due to their virtual nature, they offer unlimited possibilities to interact through different ways. This generates sometimes some trouble on the user side because from one device to another, and even in the same device, user can be faced with different practices. But it is also a great opportunity for users with disabilities to get an adapted keyboard to their specific needs, and also for standard users in a specific situation to find adapted keyboard that fit well their situation.

ISO/IEC 22121 consists of the following parts:

— ISO/IEC 22121-1 provides an overview of what virtual keyboards are. It describes virtual keyboards such as audio keyboards, visual on-screen keyboards and tactile keyboards.

— ISO/IEC 22121-2 provides guidelines on the design of standard on-screen tactile keyboards that are mainly focused on visualization: they are visually displayed, and keys are pointed at.

— ISO/IEC 22121-3 provides guidelines on the design of specific keyboards dedicated to specific interaction modes that don’t constrain user to point at keys and that can offer a wide range of displays.

Information technology — Virtual keyboards user interface — Part 1: General guidance and requirements

This document provides general requirements and recommendations for all forms of virtual keyboards including audio keyboards, on-screen or projected keyboards.

This document does not apply to physical keyboards that use real material keys or adaptable keys, which can be customized to user needs, for example with LCD display.

There are no normative references in this document.

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

3.1

on-screen keyboard

virtual keyboard (3.3) displayed on any type of screen

Note 1 to entry: On-screen keyboards are one specific type of virtual keyboards (3.3), probably the most common, that use a screen to display a keyboard.

Note 2 to entry: This type of virtual keyboard (3.3) can be used on personal computer’s screens, on mobile phones, tablets, TVs, kiosks, whiteboards.

3.2

physical keyboard

mechanical or electronic input device using an arrangement of buttons or keys

Note 1 to entry: Some physical keyboards can be adaptable (for example, using LCD screens instead of keys with printed symbols and characters).

3.3

virtual keyboard

software alternative to a physical keyboard (3.2)

Note 1 to entry: It includes audio keyboards, visual on-screen keyboards, tactile keyboards, projected keyboards.

EXAMPLE 1: Visual on-screen keyboards (3.1) are available on touch screens.

EXAMPLE 2: Visual virtual keyboard (3.3) can be projected on a table or a white board.

EXAMPLE 3: Speech keyboards used by speech-motor impaired users are vocalized and the user activates a switch in order to select the adequate letter.

3.4

keyboard layout

physical, visual or functional arrangement of the keys on a keyboard

Note 1 to entry: Contrary to physical keyboards (3.2), on-screen keyboards (3.1) do not rely on mechanical keys and printed/engraved labels, therefore, their layout can be changed conveniently by the user with the device’s user interface.

Note 2 to entry: Some physical keyboards (3.2) provide ways to change the visual arrangement of keys (for example physical keyboards (3.2) with LCD/LED displayed keys).

Note 3 to entry: An on-screen keyboard (3.1) layout may give access to one or multiple sets of characters.

Note 4 to entry: Keyboard layouts may be defined by national, regional or local standards.

3.5

focus

current selected row or column set of characters, or individual item

3.6

cursor

special indicator used for text manipulation to mark the active position

Note 1 to entry: ISO/IEC 10741-1 deals with cursor control.

Note 2 to entry: A cursor is not a pointer (3.7) icon, and both a cursor and a pointer (3.7) icon can be available and visible at the same time.

[SOURCE: ISO/IEC 11581-3:2000, 4.1]

3.7

pointer

icon displayed on a screen that a user can move with a pointing device, such as a mouse, to select items

[SOURCE: ISO/IEC 2382:2015,2126058, modified ─ “<computer graphics>” is deleted and ”symbol” replaced by “icon”]

3.8

scanning

successively moving a focus (3.5) to scan through items

3.9

tap

single consecutive touch and release actions on a touch screen device, typically it finishes shorter than 500 ms

Note 1 to entry: The touch action can be performed by any part of the human body (usually, the fingers), a pen, stylus, or any other stylus shaped object.

Note 2 to entry: ISO/IEC 14754 provides a definition for “tap” but is restricted to pen based systems.

3.10

prediction

software-generated set of characters, i.e. word, phrase or text, based on user typing that can be selected as next input for faster typing

3.11

word prediction

generation of a set of words, of which one can be used next

3.12

arrow key

key used to move a cursor (3.6) or a focus (3.5) to left, right, up or down within and between user interface objects

Note 1 to entry: An arrow key is indicated as one of left, right, up or down direction arrow graphical symbols.

3.13

end key

key used to move a cursor (3.6) or a focus (3.5) to the end of a group of user interface objects

3.14

enter key

key associated with an enter or return function

Note 1 to entry: An enter key is used to activate a focused item when it is used as a control of the virtual keyboard (3.3).

[SOURCE: ISO/IEC 9995-9:2026, 3.5, modified ─ Note 1 to entry has been added.]

3.15

home key

key used to move a cursor (3.6) or a focus (3.5) to the beginning of a group of user interface objects

3.16

navigation key

key used to move a cursor (3.6) or a focus (3.5) within and between user interface objects

Note 1 to entry: The arrow, tab, space, enter, home, and end keys can be used as navigation keys.

3.17

space key

key associated with character U+0020 SPACE

Note 1 to entry: A space key can be used to activate a focused item when it is used as a control of the virtual keyboard (3.3).

[SOURCE: ISO/IEC 9995-9:2026, 3.12, modified ─ Note 1 to entry has been added.]

3.18

tab key

key used to move a focus (3.5) to the previous or the next user interface object

Note 1 to entry: A tab key associated with Tabulation left or right function to move a cursor (3.6) during text input.

3.19

graphic character

character, other than a control function, that has a visual representation normally handwritten, printed or displayed

Note 1 to entry: Graphic characters with no visual representation can still be used, as per ISO/IEC 9995-7.

[SOURCE: ISO/IEC 9995-1:2026, 3.1, modified ─ Note 1 to entry has been added]

3.20

graphic symbol

visual representation of a graphic character (3.19), a control function, or a combination of one or more either graphic characters or control functions, or both

[SOURCE: ISO/IEC 9995-1:2026, 3.15]

3.21

symbol

any graphic symbol (3.20), which is neither a letter nor a digit

[SOURCE: ISO/IEC 9995-9:2026, 3.16, modified ─Note 1 to entry has been deleted.]

A virtual keyboard is in conformance with this document if it meets the requirements of Clause 7.

A virtual keyboard is not a physical keyboard: it has no physical keys, but instead, virtual ones.

A virtual keyboard typically appears on the screen only temporarily when character input is required and does not always require physical presence.

Virtual keyboards have functionalities similar to other physical keyboards. Virtual keyboards shall be displayed and manipulated but also enable many different displays and manipulations and offer to generate a wide range of outputs.

Virtual keys are displayed to the user. They can be either tactilely or visually displayed but can also be available through audio.

An on-screen or projected virtual keyboard can have virtual keys that are displayed on a screen or a board in a 2D space. The support can be a simple screen or a board, but it can also be enriched with audio or tactile information.

Figure 1 shows an on-screen virtual keyboard displayed on a non-touch screen, with visual feedback of the focus and with or without audio rendering or haptic rendering.

Figure 1 — An on-screen virtual keyboard on a PC (Microsoft BÉPO French virtual keyboard)

Figure 2 shows an on-screen virtual keyboard displayed on a touch screen interface

Figure 2 —An on-screen virtual keyboard on a smartphone (BÉPO French virtual keyboard)

Figure 3 shows a projected virtual keyboard displayed on a table without haptic rendering nor audio rendering.

Figure 3 — A projected virtual keyboard displayed on a table

An on-air virtual keyboard can have virtual keys that are displayed in a 3D space. The display can be done through augmented glasses or a screen and can be with or without audio and a touch screen.

Figure 4 shows an on-air virtual keyboard displayed in a 3D space without haptic rendering.

Figure 4 — Example of an on-air virtual keyboard (K-Glass KAITS)

Figure 5 shows an on-air virtual keyboard displayed in a 3D space augmented with haptic rendering.

Figure 5 — An on-air virtual keyboard with a virtual reality glove (VRGluv)

An audio virtual keyboard can have virtual keys broadcasted in an audio stream that can be navigated through with touch gestures by the user. It can be visually and tactilely displayed in parallel, but it is mainly audio oriented.

Figure 6 shos an audio virtual keyboard.

Figure 6 — An audio virtual keyboard (Tactile Easy by Orange^[9])

A braille virtual keyboard can generate braille characters from a six dot matrix displayed on a touch screen. It is made of a six tactile dot combination.

Figure 7 shows a braille virtual keyboard that enables to type braille characters with six fingers combination.

Figure 7 — A braille virtual keyboard on Android v5.0 OS

Virtual keys can be manipulated by the user through many ways. They can be pointed by the user, with the help of either visual, tactile or audio feedback. The aiming can be achieved through continuous pointing with a finger on a tactile surface or a mouse pointer or a gaze command on a PC, or sequential pointing with a focus on the screen managed through navigational keys on a physical keyboard or a remote control or even a single key associated to focus auto-scroll.

Continuous pointing at virtual keys can be achieved directly by a finger pointing on a tactile surface, or indirectly from a pointing device such as a mouse, a joystick or a trackpad. Continuous feedback can be given from a pointer (a circle, an arrow, a stroke). This includes pointing with some part of the body, like a finger, toe, or eyes and can be achieved with beam of light, headstick, or mouthstick. Keys can be activated each at a time or through a continuous gesture.

Figure 8 illustrates a virtual keyboard with gestural input.

Figure 8 — Gestural virtual keyboard on Android v5.0 OS

Figure 9 shows a virtual keyboard with joystick pointing and shortcuts activations.

Figure 9 — Virtual keyboard on Playstation4 (Sony)

Another way to point at virtual keys can be achieved through sequential pointing from a remote control or four directional keys on a physical keyboard. In this case a sequential feedback is given from a focus (a square around the virtual key or a highlighted virtual key).

Figure 10 illustrates a virtual keyboard on a TV screen controlled from a 4-direction device on a remote control.

Figure 10 — Virtual keyboard on wuakiTV

When the displayed keyboard is audio augmented (pointed keys are vocalized before they are activated) user can do auditory fishing.

Continuous pointing, sequential pointing and shortcuts enable direct selection. Direct selection is the fastest way to make choices.

A visually displayed keyboard can be manipulated sequentially with the help of switches through scanning method. In this case a sequential feedback is given from a focus (a square around the virtual key or a highlighted key). Scanning offers one choice at a time. A user shall stop the scanning on the key the user wants. A scanning system auto-selects a key and asks the user “Is this what you want?”. The system will keep asking user this until the user gets to the right key. Some devices have lights or square around keys that pass over each choice on the screen or board. A user uses a switch to stop the light or the square on the user’s choice.

Figure 11 illustrates a virtual keyboard showing numerical and alphabetical characters and commands. This virtual keyboard is controlled from a scanning method with columns and lines selection.

Figure 11 —OnScreen with CrossScanner (IMG)

When the displayed keyboard is audio augmented (pointed keys are vocalized before they are activated) user can do auditory scanning.

Scanning methods enable selection but, due to sequential display, it takes time to choose the aimed key.

Virtual keyboards can generate a full set of outputs, from text characters or sentences, to images, sounds, pre-registered words or phrases and system commands.

Keys of virtual keyboards can display a wide range of contents such as different characters set from the same language or from different languages. They can display alphabetical or numerical characters, or symbols and images, and either braille or audio or video samples.

Figure 12 shows an AEIOU virtual keyboard, Figure 1 shows a BÉPO virtual keyboard and Figure 8 shows an AZERTY virtual keyboard, all of them are displaying French characters but their arrangements are different.

Figure 12 — Alphabetical AEIOU virtual keyboards displaying French characters (Tactile Easy by Orange^[9])

Figure 13 shows an on-screen virtual keyboard displaying symbols and images.

Figure 13 — Grid3 software from Smartbox

Virtual keyboards can be adapted to users, technical contexts, specific tasks, and specific contexts of use.

Some virtual keyboards are dedicated to specific users. They are named Augmentative and Assistive Communication (AAC) tools.

Users with some motor constraints (short- or long-term injuries, spasticity, tremor, low tone, muscle spasm, user interacting with only a mouse, or trackball, joystick, switches, head pointing, eye gaze or other part of the body) need specific interaction modes for their input method. For example, they need sometime dwell selection, tap, or use tab and enter keys for navigation.

NOTE 1 Dwell selection is achieved through pointing an interface object and waiting for a delay such as 0,3 s to select the pointed object.

NOTE 2 Moving the focus forward can be achieved through pressing tab key and to activate the focused interface object can be achieved by pressing enter key.

Some users need focus auto-scroll, or adapted touching area equivalent to physical keyguards. Word completion (to propose words) and phrase completion (to propose adding sentences) are often of great help. Some users have pointing constraints and interact with keyboard mouse commands (e. g., shortcuts or arrow keys), or vocal recognition.

Users with some cognitive constraints (as cognitive impaired user or illiterate users) need symbol based and not character based keyboards. Novice users need simplified virtual keyboards and phrase completion as well as spellchecker.

Users with visual constraints need audio enhancement for keys exploration.

Users with speech impairment need self-learning word prediction, audio enhancement, speech output when a key is selected, and a speech output when a word is selected. They need also play and pause functions in order to control the system speak out. Finally, they need to have the ability to create, to store, and to organize frequently used phrases.

Many other users have several constraints and combine several needs.

NOTE 3 ISO/IEC 29138-1 provides more information about those needs..

Virtual keyboards should be used when there is a lack of physical keyboard, in case of a tactile interface, in case of a non-tactile and distant screen display as a TV or a whiteboard.

When a user has to type regularly big documents a keyboard shall conform to typewriting rules. But those rules are different for a user that only has to type a password or to use some specific shortcuts for an application. They also differ widely in the case of a user that uses a keyboard mainly for playing purpose. Each specific task needs a specific virtual keyboard.

A user in a multitask situation, as a car driver, or a walking person with a smartphone in the user’s hand, needs a specific virtual keyboard with optimized large keys areas or specific gestural interaction modes, audio enhancement and word or phrase completion.

A user in a multi-language situation shall be able to toggle easily between different character sets.

Visual clear rendering of the key either characters or symbols shall be provided.

Figure 14 shows an example of rendering of keys that characters are in bold font and have a clear contrast from the background.

Figure 14 — Clear rendering of the key characters

The focused key shall be clearly visually distinguishable.

Figure 15 shows an example of a feedback that the focused “m” key is displayed surrounded by a square with a bold line in a different colour.

Figure 15 — Clear rendering of the feedback of the current focused key

Throughout the pressure delay, a visual feedback of the pressed key shall be provided. It should be able to disable this function when entering sensitive information.

Figures 16 shows a visual feedback that the “m” key has been pressed by half filling the key with a different colour.

Figure 16 — Key pressure feedback by half filling with a different colour

Figure 17 shows another visual feedback that upon the pressed “m” key, an “m” character is displayed throughout the pressure action.

Figure 17 — Key pressure feedback by bubble

At the end of the pressure delay of a key located in the keys area of the virtual keyboard a visual output of the pressed key shall be displayed.

EXAMPLE 1 The pressed A key generates a “A” character in the output field.

EXAMPLE 2 At the end of the pressure action a “A” character moves from the pressed A key to the output field.

EXAMPLE 3 The activation of the “Hello” predicted word generates a zoom in effect of this word that moves to the output field.

Virtual keyboards that provide a visual display shall provide the following settings for available visual enhancements.

a) key size: key should be adjustable in size, at least a user should be able to choose between small and large keyboard

b) colour combination: pair of foreground and background colours shall be selectable

NOTE The user can set paired colours (blue letters and yellow background) that are more appropriate to the user’s needs.

c) contrast: key symbols and background shall be adjustable in contrast

EXAMPLE 1 Figure 18 shows a high contrast display that the result of the user set the visual display of the keyboard to black background with white bold letters.

Figure 18 — Key characters displayed in high contrast

d) focus: focus display shall be adjustable in contrast

EXAMPLE 2 Figure 19 shows a focus display in high contrast that the result of the user adjusted the focus to high contrast with a large white bold frame.

Figure 19 — Focus displayed in high contrast

The following requirements address to virtual keyboards, i.e. projected, on-air, audio and brail, whether they are pointed at or sequentially browsed, and regardless of what they contain (character keys, symbols or images).

An audio rendering of the focused key shall be available to be played. Each key content shall be described in order to be played by a vocal synthesis.

NOTE 1 The system plays an audio output of the nature of the focused key. For example, when the A key is focused, an “A” sound is played and when a word “Hello” from a predictive key is focused, a “Hello” sound is played.

Generic audio feedback of a focused key shall be available to be played.

NOTE 2 The system plays an audio output of the selection status of the focused key, but not its nature, i. e. when any key is focused, a “bip” sound is played.

NOTE 3 The generic audio feedback is not played when the audio rendering is activated, i. e. when the A key is focused, an “A” sound is played but there is no “bip” sound.

Generic audio feedback of a pressed key shall be available to be played.

NOTE 4 The pressed A key generates a “clonk” sound.

At the end of the pressure delay of a key located in the keys area of the virtual keyboard an audio output (echo sound) of the pressed key shall be available to be played.

NOTE 5 This audio output plays the nature and the status of the pressed key, i. e. the pressed A key generates an “A typed” sound (where “A” is the nature and “typed” is the status) or the pressed A key generates an “A” sound generating a different intonation (where “A” is the nature and where the different intonation expresses the status).

NOTE 6 In case of a key command, the “nature” played depends upon the aimed interface object, i. e. the pressed backspace/backward erase key generates a “X erased” (where “X” is the nature of the erased character and “erased” the status) and the pressed Escape key generates a “Window Y closed” (where “Y” is the nature of the closed window and “closed” the status).

Virtual keyboard audio settings should enable to adjust to only play the nature of the focused key.

NOTE 7 When the A key is focused, an “A” sound is played. No other sound is played when the key is pressed.

Virtual keyboard audio settings should enable to only play the pressed key.

NOTE 8 When the A key is focused, no sound is played. The pressed A key generates a “clonk” or an “A typed” sound.

Virtual keyboard audio settings should enable to play both focused key and pressed key.

NOTE 9 When the A key is focused, an “A” sound is played. And when the A key is pressed then it generates an “A typed” sound.

Virtual keyboard audio settings should enable to shut off audio.

A virtual keyboard should provide a word completion technology for accelerating text input.

A virtual keyboard should provide self-learning word prediction to be adapted to user.

A virtual keyboard should provide creating and organizing frequently used phrases to optimize user task.

A virtual keyboard should provide customization options, such as:

a) visual enhancements;

b) audio enhancements;

c) keys labels and images personalization;

d) keys organization in categories and sub-categories;

e) key mapping to associate a keystroke with an aimed command or character;

f) new key creation;

g) time delay settings.

A virtual keyboard should provide functions to load-save and share a customized keyboard.

Bibliography

[1] ISO/IEC 2382:2015, Information technology — Vocabulary

[2] ISO/IEC 9995‑1:2026, Information technology — Keyboard layout for text and office systems — Part 1: General principles governing keyboard layouts

[3] ISO/IEC 9995‑7:2026, Information technology — Keyboard layout for text and office systems — Part 7: Graphical symbols used to represent functions

[4] ISO/IEC 9995‑9:2026, Information technology — Keyboard layout for office systems — Part 9: Multi-lingual, multiscript keyboard layouts

[5] ISO/IEC 10741‑1:1995, Information technology — User system interfaces — Dialogue interaction — Part 1: Cursor control for text editing

[6] ISO/IEC 11581‑3:2000, Information technology — User system interfaces and symbols — Icon symbols and functions — Part 3: Pointer icons

[7] ISO/IEC 14754:1999, Information technology — Pen-Based Interfaces — Common gestures for Text Editing with Pen-Based Systems

[8] ISO/IEC 29138‑1:2018, Information technology — User interface accessibility — Part 1: User accessibility needs

[9] Chêne, D., Petit, É., Zijp-Rouzier S. (2016). How to Achieve Design for All. Chapter · July 2016. DOI: 10.1007/978-3-319-40244-4_12, In book: Universal Access in Human-Computer Interaction. Interaction Techniques and Environments, pp.117-128