Table of contents

[9 Input devices 9-1](#input-devices)

[9.1 Keyboards 9-4](#keyboards)

[9.2 Fixed-function keys 9-6](#fixed-function-keys)

[9.3 Pointing devices 9-7](#pointing-devices)

[9.3.1 General 9-7](#general)

[9.3.2 Mouse 9-9](#mouse)

[9.3.3 Joystick and trackball 9-10](#joystick-and-trackball)

[9.3.3.1 General 9-10](#general-1)

[9.3.3.2 Hand-operated displacement joysticks
9-10](#hand-operated-displacement-joysticks)

[9.3.3.3 Finger-operated displacement joysticks
9-11](#finger-operated-displacement-joysticks)

[9.3.3.4 Thumb tip and fingertip-operated displacement joysticks
9-13](#thumb-tip-and-fingertip-operated-displacement-joysticks)

[9.3.3.5 Hand-operated isometric joysticks
9-13](#hand-operated-isometric-joysticks)

[9.3.3.6 Thumb tip and fingertip-operated isometric joysticks
9-14](#thumb-tip-and-fingertip-operated-isometric-joysticks)

[9.3.3.7 Ball controls 9-14](#ball-controls)

[9.3.4 Light pen 9-16](#light-pen)

[9.3.5 Stylus and grid 9-17](#stylus-and-grid)

[9.3.6 Pointer shapes 9-18](#pointer-shapes)

[9.3.7 Pointing device buttons 9-20](#pointing-device-buttons)

[9.4 Alternative input devices (non-keyboard, non-pointing devices)
9-21](#alternative-input-devices-non-keyboard-non-pointing-devices)

[9.4.1 General 9-21](#general-2)

[9.4.2 Touch interactive devices/Touch panels
9-22](#touch-interactive-devicestouch-panels)

[9.4.3 Voice control 9-25](#voice-control)

[9.5 Interchangeability among input devices
9-25](#interchangeability-among-input-devices)

[9.6 Accommodating people with disabilities
9-26](#accommodating-people-with-disabilities)

[Glossary 9-28](#__RefHeading___Toc30292683)

[References 9-29](#__RefHeading___Toc30292684)

[Index 9-30](#__RefHeading___Toc30292685)

List of exhibits

[Exhibit 9.0 Advantages and disadvantages of non-keyboard input devices
9-1](#__RefHeading___Toc30293321)

[Exhibit 9.0 (cont.) Advantages and disadvantages of non-keyboard input
devices 9-2](#__RefHeading___Toc30293322)

[Exhibit 9.0 (cont.) Advantages and disadvantages of non-keyboard input
devices 9-3](#__RefHeading___Toc30293323)

[Exhibit 9.1.15 Cursor movement keys 9-5](#__RefHeading___Toc30293324)

[Exhibit 9.3.2.5 Dimensions of a mouse 9-9](#__RefHeading___Toc30293325)

[Exhibit 9.3.3.3.1 Finger-operated displacement joystick specifications
9-12](#__RefHeading___Toc30293326)

[Exhibit 9.3.3.7.1 Ball control specifications
9-15](#__RefHeading___Toc30293327)

[Exhibit 9.3.6.1 Pointer shapes associated with functions
9-19](#__RefHeading___Toc30293328)

[Exhibit 9.4.2.4 Touch panel responsive area dimensions
9-24](#__RefHeading___Toc30293329)

#  Input devices

This section provides rules for keyboards, function keys, pointing
devices, and some alternative input devices. The advantages and
disadvantages of non-keyboard input devices are shown in Exhibit 9.0.
The characteristics of these devices need to be considered in the
selection of the appropriate controls for a given task.

At times, the line between what is considered a control and what is
considered an input device can be blurred, such as the use of
pushbuttons in conjunction with trackballs in some systems and the use
of knobs to adjust parameters (such as range) in other systems.
Information on pushbuttons, knobs, dials, and switches is contained in
Chapter 6, Controls and Visual Indicators.

[]{#__RefHeading___Toc30293321 .anchor}**Exhibit 9.0** Advantages and
disadvantages of non-keyboard input devices

  ------------- ----------------------- -------------------------------------
  **Type of     **Advantages**          **Disadvantages**
  device**                              

  Mouse         Relatively fast         Requires additional flat work surface

                Has low error rates for Difficult to use for free-hand
                large targets           graphic input

                Allows user to          High error rates with small targets
                concentrate attention   
                on VDT screen           

                                        Lost time when mouse held backwards
                                        or sideways

                                        Some training needed

                                        Wheel (ball) slipping sometimes a
                                        problem

  Directional   Can be used comfortably Slower than the light pen and other
  controllers   with minimum fatigue    "point-to-devices" for simple input
  (joystick and                         and option selections
  trackball)                            

                Does not cover parts of Must be attached, but not to the
                the screen in use       display

                Expansion or            Unless there is a large joystick, an
                concentration           inadequate control to display ratio
                                        will result for positional control

                Ball control is an      The displacement of the stick
                efficient use of space  controls both the direction and the
                                        speed of cursor movement

                                        Trackball and joystick controllers
                                        are difficult to use for accurate
                                        free-hand graphic input

                                        Difficult to integrate the activate
                                        switch with the trackball
  ------------- ----------------------- -------------------------------------

[]{#__RefHeading___Toc30293322 .anchor}**Exhibit 9.0 (cont.)**
Advantages and disadvantages of non-keyboard input devices

  -------- ----------------------- ---------------------------------------
  Light    Fast for simple input   May not feel natural to user, like a
  pen                              real pen or pencil does

           Good for tracking       Requires some fine motor control
           moving objects          

           Minimal perceptual      May lack precision because of the
           motor skills needed     aperture distance from the CRT screen
                                   surface, and parallax

           Efficient for           Contact with the computer may be lost
           successful multiple     unintentionally
           selection               

           User does not have to   Frequently requires simultaneous button
           scan to find a cursor   depression may cause slippage and
           somewhere on the screen inaccuracy

           May be adaptable to bar Must be attached to terminal, which may
           coding                  be inconvenient

                                   Glare problem if pen tilted to reduce
                                   arm fatigue

                                   Fatiguing if pen is held perpendicular
                                   to work surface

                                   If pointing to dark area, may require
                                   user to flash the screen to find pen

                                   One-to-one input only (zero order
                                   control)

                                   May be cumbersome to use with
                                   alternate, incompatible entry methods,
                                   like the keyboard

                                   Tends to be used for purposes other
                                   than originally intended, such as for
                                   key depression

                                   Tends to be fragile

                                   Hand may obstruct a portion of screen
                                   when in use

                                   Care must be taken to provide adequate
                                   "activate" area around choice point

                                   Cannot be used on gas plasma panel
  -------- ----------------------- ---------------------------------------

[]{#__RefHeading___Toc30293323 .anchor}**Exhibit 9.0 (cont.)**
Advantages and disadvantages of non-keyboard input devices

  ------------ --------------------- --------------------------------------
  Stylus and   Good for graphic      Extra space required on work surface
  grid         entry                 

               Can be designed to be Displacement of visual feedback from
               used on horizontal    motor activity may cause coordination
               surface               problems

               Multipurpose input    Entering hand printed characters to be
               device                recognized by the system is very slow
                                     (fewer than 40 characters/min)
                                     compared with typewriter entry
                                     (averaging 200 recognition
                                     characters/min)

               Minimal difficulty    Entering hand printed characters to be
               going from graphic    recognized by the system is very slow
               input if character is (fewer than 40 characters/min)
               built into the        compared with typewriter entry
               system, and the       (averaging 200 recognition
               tablet is used for    characters/min)
               the input             

               Spatial               
               correspondence        
               between displays and  
               control movement      

  Touch screen No separate input     Low resolution
               device                

               Fast                  Finger can block view

                                     Fingerprints on screen

                                     Tires arm

  Voice        Does not require      Entry can be slow
  activation   hands                 

               Does not require user Must use specified vocabulary
               to shift gaze         

               Useful for low light  Some systems must be individualized to
               conditions            specific user

               Allows simultaneous   If individual's voice changes (for
               activation of more    example, become stressed) system may
               than one control mode not respond

               Could be used in lieu May require headset
               of a translator,      
               allowing natural,     
               conversational        
               version of different  
               languages to control  
               complicated systems   

                                     Speaker-dependent systems require
                                     template loading time
  ------------ --------------------- --------------------------------------

## 9.1 Keyboards

Keyboards vary greatly in the number and arrangement of keys. Most
keyboards include the following:

a.  **Alphanumeric keys -** The letters of the alphabet, numerals, and
    punctuation symbols (numeric keypads may be separate on portable
    computers).

b.  **Dedicated formatting keys** - Keys for text formatting operations
    such as a **Space** bar, a **Tab** key, and a **Return** or
    **Enter** key.

c.  **Modifier keys** - Keys that modify or qualify the effects of other
    keys for as long as they are held down, for example, **Shift,
    Ctrl,** and **Alt.**

d.  **Navigation keys** - Keys that move a cursor, for example,
    **Arrow** keys, **Home, End, Page Up,** and **Page Down.**

e.  **Fixed-function key** - Keys provided for extra or general
    functions, typically labeled **F1, F2,** and so on.

f.  **Special purpose keys** - Keys that have a special function, such
    as **Help, Delete,** and **Backspace.**

-   **9.1.1** **When to use.** If applicable, keyboards shall be
    provided for the entry of alphabetic, numeric, and other special
    characters into the system. \[Source: Department of Defense,
    (MIL-STD-1472D), 1989\]

-   **9.1.2** **Include a numeric keypad for entering numeric data.** If
    an application requires substantial and repetitive input of numeric
    data, the keyboard shall include a numeric keypad. \[Source:
    MIL-STD-1472D, 1989; Department of Defense (MIL-STD-1801), 1987\]

-   **9.1.3** **Numeric keyboards.** Keyboards intended solely for the
    entry of numbers shall have the numerals \"1\" through \"9\"
    arranged in a three by three array, with \"0\" centered below the
    bottom row. \[Source: Department of Energy (DOE-HFAC1), 1992\]

-   **9.1.4** **Numeric keyboards for communication.** If the keyboard
    will be used primarily for communications, it shall use the
    \"telephone\" arrangement, that is, with the numerals 1, 2, and 3 in
    the top row. \[Source: DOE-HFAC1, 1992\]

-   **9.1.5** **Numeric keyboards for number manipulation.** If the
    keyboard will be used primarily for manipulating numbers, it shall
    use the \"calculator\" arrangement, that is, with the numerals 1, 2,
    and 3 in the bottom row. \[Source: DOE-HFAC1, 1992\]

-   **9.1.6** **Alphanumeric keyboards.** Keyboards intended for the
    entry of both alphabetic and numeric information shall conform to
    the standard \"QWERTY\" arrangement. \[Source: DOE-HFAC1, 1992\]

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-   **9.1.7 Key size.** The minimum horizontal surface width for a key
    on a typing keyboard should be 12 mm. \[Source: American National
    Standard Institute(ANSI), 1988\]

-   **9.1.8** **Horizontal spacing of keys.** Horizontal centerline
    distances should be between 18-19 mm. \[Source: ANSI, 1988\]

-   **9.1.9** **Vertical spacing of keys.** Vertical centerline
    distances should be between 18-21 mm. \[Source: ANSI, 1988\]

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-   **9.1.10** **Force to depress keys.** The maximum force needed to
    depress keys shall measure between 0.25N and 1.5N with a preferred
    range between 0.5N and 0.6N. \[Source: ANSI, 1988\]

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-   **9.1.11** **Keyboard slope.** The slope of the keyboard for typing
    should be between 0 and 25 degrees, preferably less than 15 degrees.
    \[Source: ANSI, 1988\]

-   **9.1.12** **Standard keyboards.** If feasible, standard keyboards
    should be used. Nonstandard keyboards should contain only those keys
    that are used by the keyboard user. \[Source: Nuclear Regulatory
    Commission (NUREG-0700), 1996; DOE-HFAC1, 1992\]

**Discussion.** The presence of non-relevant keys, such as those that
might be used by programmers, adds to keyboard complexity and may induce
errors. \[Source: NUREG-0700, 1996; DOE-HFAC1, 1992\]

-   **9.1.13** **Two-dimensional cursor control.** If a keyboard will be
    used for text processing, it shall provide for movement of the
    cursor in two dimensions, for example by including a set of cursor
    control keys. \[Source: DOE-HFAC1, 1992\]

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-   **9.1.14** **Cursor control key layout.** If cursor control keys are
    included, they should be arranged in a two-dimensional array.
    \[Source: DOE-HFAC1, 1992\]

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-   **9.1.15** **Cursor movement keys.** Cursor movement keys shall be
    arranged in a spatial configuration reflecting the direction of
    actual cursor movement. Exhibit 9.1.15 shows the arrangement of
    cursor movement keys. \[Source: National Aeronautics and Space
    Administration (NASA-STD-3000A), 1989; DOE-HFAC1, 1992\]

> []{#__RefHeading___Toc30293324
> .anchor}![](media/image1.png){width="3.625in"
> height="1.65625in"}Cursor movement keys

-   **9.1.16** **Positive feedback.** Where applicable, feedback shall
    be provided to inform the operator that the intended key was pressed
    and that the next operation may be initiated. \[Source:
    MIL-STD-1472F, 1999\]

-   **9.1.17** **Changing data.** Users shall be provided a means to
    change previous entries by delete, backspace, and insert actions.
    \[Source: MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

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-   **9.1.18** **Keyboard equivalents to function keys.** If an
    application assigns operations to function keys, the operations that
    can be performed with a function key should also be performable with
    alphanumeric keys. \[Source: Keane (DISA HCISG V1.0), 1992\]

-   **9.1.19** **Keyboard equivalents to pointing device operations.**
    If an application provides both a keyboard and a pointing device,
    the operations that can be performed with the pointing device should
    also be performable with the keyboard. \[Source: DISA HCISG V1.0,
    1992\]

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-   **9.1.20** **Consistent keyboards.** If a system contains more than
    one keyboard, the configuration of alphanumeric, numeric, and
    special function keys shall be consistent throughout the system.
    \[Source: MIL-STD-1472F, 1999\]

## 9.2 Fixed-function keys

-   **9.2.1** **Standardization.** Fixed-function keys should be
    standardized throughout the system. \[Source: MIL-STD-1472D, 1989;
    DOE-HFAC1, 1992\]

-   **9.2.2** **Availability.** Fixed-function keys should be selected
    to control functions that are continuously available; that is, the
    lock out of fixed-function keys should be minimized. Mechanical
    overlays should not be used to lock out function keys. \[Source:
    MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

-   **9.2.3** **Non-active keys.** When a keyboard is dedicated for use
    with only a specific application, blank keys on the keyboard should
    replace non-active fixed-function keys. \[Source: MIL-STD-1472D,
    1989; DOE-HFAC1, 1992\]

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-   **9.2.4** **Grouping.** Fixed-function keys shall be grouped
    logically and shall be placed in distinctive locations. \[Source:
    MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

## 9.3 Pointing devices

> This section contains rules for pointing devices in general, the shape
> of the pointer itself, and buttons on pointing devices.

**Definitions.** A **pointing device** is a non-keyboard device that
allows a user to navigate rapidly around the screen and to specify and
select objects for manipulation and action. Examples include a mouse,
trackball, stylus and grid, and light pen. A **pointer** is a symbol
displayed on the screen that is controlled by a pointing device. Its
shape may change depending on the function that is invoked at a
particular moment or its location on the screen.

### 

### 9.3.1 General

-   **9.3.1.1** **Functionality.** When present, a pointing device shall
    be capable of (1) moving a pointer on the screen, (2) selecting
    objects on which the pointer is placed, and (3) drop and drag
    operations. \[Source: Department of the Navy (DON UISNCCS), 1992\]

-   **9.3.1.2 Single pointer.** A pointing device shall be associated
    with a single pointer on the screen. \[Source: DON UISNCCS, 1992\]

-   **9.3.1.3** **Moving the pointer.** A user shall be able to move the
    pointer on the screen by moving all or part of the pointing device.
    The pointer shall move in the same direction that the pointing
    device moves. A user shall be able to move the pointer anywhere on
    the screen. \[Source: DON UISNCCS, 1992\]

-   **9.3.1.4** **Non-disappearance of pointer.** A pointer shall not
    move beyond the outer boundaries of the screen nor shall it
    disappear from sight. \[Source: DON UISNCCS, 1992\]

**Exception.** When there is another screen adjacent to the first, the
pointer may move from one screen to the other. This rule does not apply
when a cursor is moved quickly and the screen refresh rate is too slow
to show the full path of the cursor. \[Source: DON UISNCCS, 1992\]

-   **9.3.1.5** **Control of the pointer.** A pointer should not move on
    the screen unless a user moves the pointing device. That is, an
    application should not move a pointer arbitrarily. \[Source: DON
    UISNCCS, 1992\]

**Exceptions.** One exception to this rule is if an application
automatically moves the pointer in conjunction with the scroll bar. For
example, when the user clicks on the down arrow to scroll through a
document, the application may automatically move the pointer so that the
pointer will remain on the scroll arrow.

Another case may be when the pointer \"jumps\" or \"snaps-to\" a default
button because the user has selected that default option. \[Source: DON
UISNCCS, 1992\]

-   **9.3.1.6** **Pointer stability.** The stability of the pointer
    shall be within 1.3 mm (0.05 in) in any direction; the preferred
    stability is within 0.25 mm (0.01 in). \[Source: DON UISNCCS, 1992\]

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-   **9.3.1.7** **Movement ratio.** The ratio of movement of the
    pointing device to the movement of the pointer should default to
    approximately 1:1 and be adjustable by the user. \[Source: DON
    UISNCCS, 1992\]

-   **9.3.1.8** **Type of device.** The pointing device selected for an
    application should be the one thatmost appropriately meets the
    application requirements and is most cost-effective. The
    appropriateness of some specific types of pointing devices for tasks
    is as follows:

a.  A **mouse** is a general purpose-pointing device suitable for a wide
    range of applications.

b.  A **joystick** is appropriate for tasks requiring precise
    adjustments and continuous control.

c.  A **trackball** is appropriate for generating precise X and Y output
    values and cumulative travel in any direction.

d.  A **light pen** is appropriate for non-critical, imprecise
    functions, especially if the primary task is item selection.

e.  A **stylus and grid** is appropriate for graphic entry. \[Source:
    MIL-STD-1472D, 1989; MIL-STD-1801, 1987\]

**Discussion.** Another factor that may contribute to the
appropriateness of a given input device is the expectations,
experiences, or preferences of the intended user population. If a given
user population has a wealth of experience, familiarity, or acquired
skill with a particular type of device, careful consideration needs to
be given to replicate the features, functionality, performance, and
\"feel\" to which they are accustomed. \[Source: MIL-STD-1472D, 1989;
MIL-STD-1801, 1987\]

### 9.3.2 Mouse

-   **9.3.2.1** **Use.** A mouse should be used for zero order control
    only (for example, the generation of X and Y outputs by the
    controller results in proportional displacement of the pointer).
    \[Source: MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

**Discussion.** This type of pointing device may be used on any flat
surface to generate X and Y coordinate values that control the position
of the pointer on the associated display. It may be used for data pick
off or for entry of coordinate values. \[Source: MIL-STD-1472D, 1989;
DOE-HFAC1, 1992\]

-   **9.3.2.2** **Dynamic characteristics.** The design of the mouse and
    the placement of the maneuvering surface shall allow the user to
    consistently orient the mouse within 10° of the correct orientation
    without visual reference to the mouse. \[Source: MIL-STD-1472D,
    1989; DOE-HFAC1, 1992\]

**Discussion.** If the user grasps the mouse in what seems to be the
correct orientation and moves it rectilinearly along what is assumed to
be straight up the Y-axis, then the direction of movement of the cursor
on the CRT is to be between 350° and 10°. \[Source: MIL-STD-1472D, 1989;
DOE-HFAC1, 1992\]

-   **9.3.2.3** **Easily moved.** The mouse shall be easy to move in any
    direction without a change of hand grasp. \[Source: MIL-STD-1472D,
    1989; DOE-HFAC1, 1992\]

-   **9.3.2.4** **Lateral range.** A complete lateral movement of the
    mouse from side to side within the maneuvering area (such as a mouse
    pad) shall move the pointer from side to side on the display
    regardless of the scale setting or offset unless expanded movement
    is selected for an automatic sequencing mode of operation. Users
    shall be able to specify or modify the lateral movement ratio.
    \[Source: MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

-   **9.3.2.5** **Dimensions and shape.** The mouse shall have no sharp
    edges but shall be shaped roughly as a rectangular solid, with
    limiting dimensions as shown in Exhibit 9.3.2.5. \[Source:
    MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

[]{#__RefHeading___Toc30293325 .anchor}**Exhibit 9.3.2.5** Dimensions of
a mouse

### 9.3.3 Joystick and trackball

Joysticks and trackballs are appropriate to use if precise input
functions are required. They are most useful when used to control direct
pointing, rather than discrete controls such as cursor control keys.

#### 9.3.3.1 General 

-   **9.3.3.1.1 Activation and deactivation.** A discrete mechanism
    shall be provided to allow the user to activate and deactivate the
    joystick or trackball. \[Source: MIL-STD-1472D, 1989; DOE-HFAC1,
    1992\]

**Definitions.** A **displacement joystick** is a joystick that moves in
the direction it is pushed. Displacement joysticks are usually
spring-loaded so that they return to their center position. An
**isometric joystick** responds to the amount and direction of pressure
applied to it, but it does not move. Displacement joysticks usually
require less force than isometric joysticks and are thus less fatiguing
over long operating periods.

#### 9.3.3.2 Hand-operated displacement joysticks

-   **9.3.3.2.1** **Specifications.** The handgrip length of a
    hand-operated displacement joystick shall be in the range 110 to 180
    mm (4.3 to 7.1 in); the grip diameter shall not exceed 50 mm (2 in);
    clearance shall be at least 100 mm (4 in) to the side and 50 mm (2
    in) to the rear. If the joystick is contained in a separate module,
    the module shall be mounted to allow operation of the joystick
    without the base slipping, moving, or tilting. \[Source:
    MIL-STD-1472F, 1999\]

-   **9.3.3.2.2 Movement characteristics.** Movement shall not exceed
    45° from the center position. Movement shall be smooth in all
    directions, and positioning of a follower shall be attainable
    without noticeable backlash, cross-coupling, or need for multiple
    corrective movements. If the joystick is to be used for generating
    free-drawn graphics, the CRT shall have a refresh rate sufficiently
    high to give the appearance of a continuous track when the follower
    is moved. Delay between control movement and the confirming visual
    indicator response shall be minimized and shall not exceed 0.1 sec.
    \[Source: MIL-STD-1472F, 1999\]

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-   **9.3.3.2.3** **When to use.** If accuracy is more important than
    speed, a displacement joystick should be used rather than an
    isometric joystick. If a displacement joystick is used for rate
    control, the joystick should be spring-loaded so that it returns to
    center. If a joystick will have a secondary control, a displacement
    joystick should be used rather than an isometric joystick. \[Source:
    MIL-STD-1472F, 1999\]

    **Discussion.** Uses of displacement joysticks include (1) picking
    data from a CRT, (2) generating free-drawn graphics, (3) controlling
    a vehicle, (4) aiming sensors, and (5) serving as a mounting
    platform for a secondary control such as thumb- or finger-operated
    switches. \[Source: MIL-STD-1472F, 1999\]

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-   **9.3.3.2.4** **When not to use.** Displacement joysticks shall not
    be used with automatic sequencing of a CRT cursor or tracking symbol
    if they have a dead band near the center or hysteresis. An exception
    may be made if they are instrumented for null return or zero-set to
    the instantaneous position of the joystick at the time of
    sequencing. Upon termination of the automatic sequencing routine,
    the joystick center shall again be registered to the scope center.
    \[Source: MIL-STD-1472F, 1999\]

#### 9.3.3.3 Finger-operated displacement joysticks

Finger-operated displacement joysticks are useful for free-drawn
graphics. In this application, they are not usually spring-loaded to
return to center. It is desirable that they have sufficient friction to
remain in their last position when the hand is removed.

-   **9.3.3.3.1** **Finger-operated displacement joystick
    specifications.** The dimensions, resistance, and clearance of
    finger-operated displacement joysticks shall not exceed the maximum
    or minimum values given in Exhibit 9.3.3.3.1. \[Source:
    MIL-STD-1472F, 1999\]

> []{#__RefHeading___Toc30293326 .anchor}**Exhibit 9.3.3.3.1**
> Finger-operated displacement joystick specifications

-   **9.3.3.3.2** **Mounting.** The joystick shall be mounted in a way
    that provides forearm or wrist support. If the joystick is a
    separate modular device, the module shall be mounted so that the
    joystick can be manipulated without slippage, movement, or tilting
    of its base. \[Source: MIL-STD-1472F, 1999\]\
    ![](media/image2.png){width="5.986805555555556in"
    height="5.492361111111111in"}

-   **9.3.3.3.3** **Movement characteristics.** Movement shall not
    exceed 45° from the center position. Movement shall be smooth in all
    directions, and positioning of a follower shall be attainable
    without noticeable backlash, cross-coupling, or need for multiple
    corrective movements. Control ratios, friction, and inertia shall
    meet the dual requirements of rapid gross positioning and precise
    fine positioning. Recessed mounting or pencil attachments may be
    used as indicated in Exhibit 9.3.3.3.1 to provide greater precision
    of control. If the joystick is to be used for generating free-drawn
    graphics, the CRT shall have a refresh rate sufficiently high to
    give the appearance of a continuous track when the follower is
    moved. Delay between control movement and the confirming visual
    indicator response shall be minimized and shall not exceed 0.1 sec.
    \[Source: MIL-STD-1472F, 1999\]

#### 9.3.3.4 Thumb tip and fingertip-operated displacement joysticks

-   **9.3.3.4.1** **Usage.** Thumb tip and fingertip-operated
    displacement joysticks may be mounted on a handgrip, which can serve
    as a steady rest to damp vibration or increase precision. If they
    are so mounted, the handgrip shall not itself also function as a
    joystick. \[Source: MIL-STD-1472F, 1999\]

-   **9.3.3.4.2 Mounting.** Thumb tip and fingertip-operated
    displacement joysticks shall be mounted in a way that provides wrist
    or hand support. Console-mounted joysticks shall be mounted as shown
    in Exhibit 9.3.3.3.1. \[Source: MIL-STD-1472F, 1999\]

-   **9.3.3.4.3** **Movement characteristics.** Movement shall not
    exceed 45° from the center position. If the joystick is a separate
    modular device, the module shall be mounted so that the joystick can
    be manipulated without slippage, movement, or tilting of its base.
    \[Source: MIL-STD-1472F, 1999\]

#### 9.3.3.5 Hand-operated isometric joysticks

Isometric joysticks are also known as \"stiff\" sticks, \"force\"
sticks, and \"pressure\" sticks. These joysticks have no perceptible
movement, but they can respond to the amount and direction of pressure
applied. They are appropriate for tasks requiring precise or continuous
control movement in two or more related dimensions. They are
particularly appropriate for applications in which (1) there is a need
for return to a precise center after each use, (2) feedback to the user
is primarily visual rather than tactual from the control itself, and (3)
there is minimal delay and tight coupling between the control and system
reaction. They may also be used as mounting platforms for secondary
controls, such as thumb- and finger-operated switches, although
operation of secondary controls is more likely to induce error on an
isometric handgrip than on a displacement handgrip. \[Source:
MIL-STD-1472F, 1999\]

-   **9.3.3.5.1** **Specifications.** The handgrip length of a
    hand-operated isometric joystick shall be in the range of 110 to 180
    mm (4.3 to 7.1 in). The grip diameter shall not exceed 50 mm (2 in).
    Clearances of 100 mm (4 in) to the side and 50 mm (2 in) to the rear
    shall be provided to allow for hand movement. The maximum force for
    full output shall not exceed 118 N (26.7 lb). \[Source:
    MIL-STD-1472F, 1999\]

-   **9.3.3.5.2** **Mounting.** Hand-operated isometric joysticks shall
    be mounted in a way that provides forearm support. If the joystick
    is a separate modular device, the module shall be mounted so that
    the joystick can be manipulated without slippage, movement, or
    tilting of its base. \[Source: MIL-STD-1472F, 1999\]

#### 9.3.3.6 Thumb tip and fingertip-operated isometric joysticks

-   **9.3.3.6.1** **Mounting.** Thumb tip- and fingertip-operated
    isometric joysticks shall be mounted in a way that provides wrist or
    hand support. They may be mounted on a handgrip that serves as a
    steady rest to damp vibrations or to increase precision. If they are
    so mounted, the handgrip itself shall not function simultaneously as
    a joystick controller. Console-mounted joysticks shall be mounted as
    shown in Exhibit 9.3.3.3.1. If the joystick is a separate modular
    device, the module shall be mounted so that the joystick can be
    manipulated without slippage, movement, or tilting of its base.
    \[Source: MIL-STD-1472F, 1999\]

#### 

#### 9.3.3.7 Ball controls 

Other names for ball controls are \"track ball,\" \"ball tracker,\"
\"joy ball,\" and \"rolling ball.\"

-   **9.3.3.7.1 Specifications.** The dimensions, exposure, resistance,
    and clearance of ball controls shall not exceed the maximum and
    minimum values given in Exhibit 9.3.3.7.1. \[Source: MIL-STD-1472F,
    1999\]

[]{#__RefHeading___Toc30293327 .anchor}**Exhibit 9.3.3.7.1** Ball
control specifications

\[Source: MIL-STD-1472F, 1999\]

-   **9.3.3.7.2** **Limb support.** If a ball control will be used to
    make precise or continuous adjustments, a wrist or arm support or
    both shall be provided. \[Source: MIL-STD-1472F, 1999\]

-   **9.3.3.7.3** **Movement characteristics.** A ball control shall be
    capable of rotation in any direction so as to generate any
    combination of X and Y output values. When moved in either the X or
    Y direction alone, the control shall exhibit no apparent
    cross-coupling (that is, movement of the follower in the orthogonal
    direction). There shall be no backlash apparent to the user. Control
    ratios and dynamic features shall meet the dual requirements of
    rapid gross positioning and smooth, precise fine positioning.
    \[Source: MIL-STD-1472F, 1999\]

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-   **9.3.3.7.4** **When to use.** Ball controls rotate freely in all
    directions; therefore, they are suitable for applications such as
    data pickoff and accumulative travel; however, they do not provide
    for automatic return to a point of origin. Ball controls should be
    used only as position controls, that is, applications in which a
    movement of the ball produces a proportional movement of a follower
    on a visual indicator. \[Source: MIL-STD-1472F, 1999\]

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-   **9.3.3.7.5** **Movement of a follower off a visual indicator.** If
    the application allows a ball control to move its follower off the
    edge of a visual indicator, the application shall advise the user
    how to bring the follower back onto the visual indicator. \[Source:
    MIL-STD-1472F, 1999\]

### 9.3.4 Light pen

A light pen is appropriate to use if item selection is the primary type
of data entry. For example, a light pen may be used when non-critical,
imprecise input functions are required. It may also be used as a
track-oriented readout device. It can be positioned on the display
screen to detect the presence of a computer-generated track by sensing
its refresh pattern. The display system will then present a cursor on
the designated track. With suitable additional circuitry, a cursor can
be made to track the movement of the light pen across the surface, thus
allowing it to function as a two-axis controller capable of serving the
same purposes as stylus and grid devices.

-   **9.3.4.1** **Dimensions and mounting.** A light pen shall be
    between 120 and 180 mm (4.7 and 7.1 in) long with a diameter between
    7 and 20 mm (0.3 and 0.8 in). A clip shall be provided to hold the
    light pen when it is not in use. \[Source: MIL-STD-1472D, 1989;
    DOE-HFAC1, 1992\]

-   **9.3.4.2** **Activation.** A light pen shall be equipped with a
    discrete activating and deactivating mechanism. A push-tip switch,
    requiring between 0.5 to 1.4 N (2 to 4 oz) of force to activate, is
    preferred. \[Source: MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

-   **9.3.4.3** **Feedback.** Two forms of feedback shall be provided to
    the user when using a light pen:

a.  feedback concerning the position of the light pen, preferably in the
    form of a displayed cursor or highlighting, that informs the user
    that the system is recognizing the presence of the light pen. The
    feedback shall be large enough to be seen under the point of the
    light pen.

b.  feedback that the light pen has been activated (for example, the
    push-tip switch has been triggered) and the input have been received
    by the system. \[Source: MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

### 9.3.5 Stylus and grid

> A stylus and grid is appropriate to use as a multipurpose input device
> when combined with a program for character recognition. The stylus and
> grid are also very good for graphic entry although they are much
> slower than keyboard entry for alphanumeric data.

Grid and stylus devices may be transparent media placed directly on a
visual indicator, or they may be located elsewhere, in a location that
makes stylus manipulation convenient.

-   **9.3.5.1** **Specifications.** A transparent grid used as an
    overlay on a visual indicator shall conform to the size of the
    visual indicator. A grid that is displaced from the visual indicator
    shall conform as closely as possible to the size and orientation of
    its related visual indicator. The visual indicator shall contain a
    follower that appears at the position on the visual indicator that
    corresponds (that is, has the same coordinate values) to the
    location of the stylus on the grid. \[Source: MIL-STD-1472F, 1999\]

-   **9.3.5.2** **Dynamic characteristics.** Movement of the stylus in
    any direction on the grid surface shall result in smooth movement of
    the follower in the same direction. Discrete placement of the stylus
    at any point on the grid shall cause the follower to appear at the
    corresponding coordinates and to remain steady in position as long
    as the stylus is not moved. The refresh rate of the follower shall
    be sufficiently high to ensure the appearance of a continuous track
    whenever the stylus is used for the generation of free-drawn
    graphics. \[Source: MIL-STD-1472F, 1999\]

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-   **9.3.5.3** **When to use.** Grid and stylus devices may be used for
    data pickoff from a CRT, the entry of points onto a visual
    indicator, the generation of free-drawn graphics, and similar
    control applications. These devices should be used only for zero
    order control functions, that is, applications in which displacement
    of the stylus from a reference position causes a proportional
    displacement of the follower. \[Source: MIL-STD-1472F, 1999\]

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-   **9.3.5.4** **Refresh rate.** The refresh rate for the cursor shall
    be sufficiently high to ensure the appearance of a continuous track
    whenever the stylus is used to generate free-drawn graphics.
    \[Source: NASA-STD-3000A, 1989; DOE-HFAC1, 1992\]

-   **9.3.5.5** **Remote grid size.** A remote grid shall approximate
    the size of the display. \[Source: NASA-STD-3000A, 1989; DOE-HFAC1,
    1992\]

-   **9.3.5.6** **Remote grid placement.** A remote grid shall have an
    orientation that is consistent with the directional relationships
    between them and the display without violating any anthropometrics
    rules. \[Source: NASA-STD-3000A, 1989; DOE-HFAC1, 1992\]

### 9.3.6 Pointer shapes

-   **9.3.6.1** **General-purpose pointer shape.** An arrow pointing up
    and to the left shall be the general-purpose pointer (). This and
    other examples of pointer shapes associated with specific functions
    are illustrated in Exhibit 9.3.6.1. If an application provides any
    of these functions, it shall change the pointer to the associated
    shape whenever that function is invoked. An application shall
    redefine the shape of a pointer only when the pointer is inside an
    application window (including the border). \[Source: DON UISNCCS,
    1992\]

[]{#__RefHeading___Toc30293328
.anchor}![](media/image5.png){width="6.770833333333333in"
height="8.21875in"}**Exhibit 9.3.6.1** Pointer shapes associated with
functions

-   **9.3.6.2 \"Hotspot.\"** A pointer shall have a \"hotspot,\" that is
    an active point (although this active point may not be readily
    apparent to the user). The hotspot shall indicate the precise
    location where an operation will occur. These points are specified
    for a variety of pointer shapes in Exhibit 9.3.6.1. \[Source: DON
    UISNCCS, 1992\]

**Definition.** A **hotspot** is the precise part of a screen pointer
that marks the screen position where an operation on a pointing device
will have an effect. \[Source: DON UISNCCS, 1992\]

-   **9.3.6.3** **Hotspot and pointer shape.** The screen location of a
    hotspot shall not change if the pointer changes from one shape to
    another. \[Source: DON UISNCCS, 1992\]

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-   **9.3.6.4 Additional pointer shapes.** If an application provides a
    function for which a pointer shape does not exist in Exhibit
    9.3.6.1, the application may provide a new pointer shape. If this is
    done, the new shape should (1) be easy to see, (2) obscure as little
    information as possible on the screen, (3) have a hotspot that is
    obvious and easy to locate, (4) provide a hint of its purpose,
    and (5) not be easily confused with other objects on the screen.
    \[Source: DON UISNCCS, 1992\]

### 9.3.7 Pointing device buttons

One or more buttons are provided on pointing devices to allow the
manipulation of objects on the screen.

-   **9.3.7.1** **Button operations.** A user shall be able to perform
    the following actions with any button on a pointing device:

a.  Press. Depress a button and hold it down.

b.  Release. Release a button that has been depressed.

c.  Click. Press and release a button without moving the pointing
    device.

d.  Double click. Press and release a button twice in rapid succession
    without moving the pointing device.

e.  Drag. Depress a button and move the device while holding the button
    down.

f.  Move. Move the pointing device without pressing any buttons.
    \[Source: DON UISNCCS, 1992\]

-   **9.3.7.2** **Button functions.** Each button on a pointing device
    shall have a specific function (within the context of the
    application) that is executed whenever a user presses the button. If
    the device has only one button, that button shall provide the
    \"select\" function; if it has two buttons, the left one shall
    provide the \"select\" function and the right button shall provide a
    \"menu\" function. \[Source: DON UISNCCS, 1992\]

**Definitions.** The **select function** selects or activates objects on
the screen or sets the location of the cursor. The **menu function**
causes the appearance of a menu appropriate to the location of the
pointer. \[Source: DON UISNCCS, 1992\]

**Discussion.** If applicable, a system may require that a middle button
be used for a particular function (for example, as another means to
execute a default action). An application can map a function to the
middle button if the function does not contradict or interfere with the
function assigned to this button by the system or by another
application. \[Source: DON UISNCCS, 1992\]

-   **9.3.7.3** **Left-right reversal.** A system shall provide users
    the ability to reverse the left-right operation of the buttons.
    \[Source: DON UISNCCS, 1992\]

## 9.4 Alternative input devices (non-keyboard, non-pointing devices) 

> Application developers are encouraged to use input devices in unique
> ways to support efficient user performance within an application. In
> addition, developers might determine that devices such as voice input
> or touch panels are appropriate alternatives for user input.

### 9.4.1 General

-   **9.4.1.1 Consistent interaction.** If an alternate input device is
    used in an application, the manner in which users interact with the
    device (e.g., for navigation or selection) should be consistent with
    their interactions with other input devices. \[Source: DON UISNCCS,
    1992\]

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-   **9.4.1.2** **Type of device.** The alternate input device selected
    for an application shall be the one that most appropriately meets
    the application requirements and is most cost-effective. The
    appropriateness of some specific types of input devices for tasks is
    as follows:

a.  A **touch screen or touch panel** is appropriate for data entry and
    item selection if typing skills are not required.

b.  An **optical character recognition device** is appropriate for the
    entry of formatted, printed data.

c.  A **voice input** device is appropriate if the user\'s visual and
    manual performances are constrained. \[Source: MIL-STD-1801, 1987\]

### 9.4.2 Touch interactive devices/Touch panels

A touch-interactive device (TID) is an input device that permits users
to interact with the system by pointing to objects on the display. TIDs
may degrade image quality through reduced display luminance or through
reduced display resolution. These degradations can result from the
overlaid device itself and from dirt on the surface resulting from
touching. TIDs can also introduce parallax because of the separation
between the touch surface and the image, and they can introduce glare
problems. \[Source: Avery & Bowser (DOE HFDG ATCCS V2.0), 1992\]

There are six basic types of TID.

a.  **Fixed-wire** TIDs place wires, either in parallel or in a grid, in
    front of the display. Finger contact with the wire(s) generates the
    X-Y coordinates of the user\'s touch. This technology is associated
    with minimal parallax, 70 to 80% transmissivity, and a medium to
    high degree of TID glare.

b.  **Capacitive** TIDs consist of a transparent conductive film on a
    glass overlay. Touching the surface changes a small electrical
    signal passing through the film, and this signal is converted into a
    corresponding X-Y coordinate. This technology is associated with
    minimal parallax, 85% transmissivity, and a medium amount of TID
    glare.

c.  **Resistive membrane** TIDs are \"sandwich\" devices in which a
    touch results in the contact of two conductive layers. Specific
    current and voltage levels are associated with individual X-Y
    coordinates. This technology is associated with minimal parallax, 50
    to 60% transmissivity, and a high amount of TID glare.

d.  **Infrared or light-emitting diode** TIDs use infrared transmitters
    along two perpendicular sides of the display frame and photocell
    receptors along the opposite sides of the frame. A user\'s touch
    breaks the matrix of light beams, generating appropriate X-Y
    coordinates. This technology is associated with noticeable parallax
    between the plane of the light beams and the screen surface, 100%
    transmissivity, and no TID-related glare.

e.  **Surface acoustic wave** TIDs are similar to infrared TIDs except
    that they use ultrasonic beams rather than light beams. X-Y
    coordinates are determined by differential timings in reception of
    the acoustic waves. This technology is associated with minimal
    parallax, 92% transmissivity, and a medium amount of TID glare.

f.  **Pressure-sensitive** devices use strain gauges mounted between the
    display screen and an overlay. Output voltages of these strain
    gauges are encoded into the appropriate X-Y coordinates. This
    technology is associated with minimal parallax and no TID glare.
    Transmissivity is not affected because the overlay is built into the
    display screen.

-   **9.4.2.1** **Use.** A touch panel or screen should be used to
    provide an overlaying control function to a display device (e.g., a
    CRT, an electro luminescent display, or a programmable indicator) if
    direct visual reference access and optimum direct control access are
    desired. \[Source: MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

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-   **9.4.2.2** **Luminance transmission.** Touch panels shall have
    sufficient luminance transmission to allow the display to be clearly
    readable in the intended environment. \[Source: MIL-STD-1472D, 1989;
    DOE-HFAC1, 1992\]

-   **9.4.2.3** **Positive indication.** A positive indication of
    touch-panel activation shall be provided to acknowledge the system
    response to the control action. \[Source: MIL-STD-1472D, 1989;
    DOE-HFAC1, 1992\]

-   **9.4.2.4** **Dimensions and separation.** The dimensions and
    separation of responsive areas of the touch panel shall not exceed
    the maximum and minimum values given in Exhibit 9.4.2.4. \[Source:
    MIL-STD-1472D, 1989; DOE-HFAC1, 1992\]

**Note.** The maximum values listed in the Exhibit apply to logically
grouped touch panel responsive areas. An adverse environment may warrant
larger sizes and separations.

> []{#__RefHeading___Toc30293329 .anchor}**Exhibit 9.4.2.4** Touch panel
> responsive area
> dimensions![](media/image6.png){width="3.0097222222222224in"
> height="2.7645833333333334in"}

-   **9.4.2.5** **Display feedback.** Display of user command or action
    feedback for touch panels shall not exceed 0.25 seconds. \[Source:
    MIL-STD-1472D, 1989\]

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-   **9.4.2.6** **Minimal parallax.** Touch-interactive devices should
    be selected and mounted to minimize parallax problems. \[Source:
    Avery & Bowser (DOE HFDG ATCCS V2.0), 1992\]

-   **9.4.2.7** **Minimal specular glare.** Touch-interactive devices
    should be selected and mounted to minimize specular glare. \[Source:
    DOE HFDG ATCCS V2.0, 1992\]

### 9.4.3 Voice control

-   **9.4.3.1** **Phonetically distinct vocabulary.** Spoken entries
    used for transactions should be phonetically distinct from one
    another to eliminate misinterpretation. Testing should be performed
    to determine which sounds and words or phrases could be
    distinguished reliably. \[Source: MIL-STD-1472F, 1999\]

**Discussion.** Spoken command entries are not to be chosen arbitrarily.
Tradeoffs between phonetic distinctiveness and familiarity of
terminology need to be evaluated.

-   **9.4.3.2** **Easy error correction.** Feedback and simple error
    correction procedures shall be provided for speech input so that if
    the computer has not correctly recognized a spoken entry, the user
    can easily cancel the entry and try again. \[Source: MIL-STD-1472F,
    1999\]

-   **9.4.3.3** **Alternative devices.** Alternative input devices shall
    be available so that if the system cannot recognize a voice entry
    after repeated attempts, or the device fails, another type of input
    entry can be substituted. \[Source: MIL-STD-1472F, 1999\]

## 9.5 Interchangeability among input devices

The interchangeability among input devices by the user can be useful
during specific operations. Users may want to perform some actions using
a keyboard and others actions using a pointing device. The ability to
choose which input device must be optional to the user and not a
requirement by the system.

-   **9.5.1** **Redundant control.** If more than one input device is
    present, a user should be able to control computer interaction with
    all of them. For example, a keyboard should be capable of executing
    navigation and selection operations when used in conjunction with a
    mouse, light pen, or other input devices. \[Source: DON UISNCCS,
    1992\]

**Discussion.** Full interchangeability is not required. It is assumed
that a user will select the input device that is most appropriate for
the task being performed. For example, a user may rely on direct
manipulation, using a pointing device such as a mouse or trackball, as
the primary means of interaction for object selection and manipulation.
Similarly, a user may use a keyboard primarily for text entry and for
object selection being performed in conjunction with or interspersed
with text entry. \[Source: DON UISNCCS, 1992\]

## 9.6 Accommodating people with disabilities

Most of the difficulty experienced by people with physical disabilities
in using computer systems stem from using input devices, such as a
keyboard or a mouse, and from handling storage media, such as computer
diskettes. \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.1 Redundant pointing functions.** A system that uses a
    pointing device, such as a mouse, should provide a means for
    carrying out all of the pointing functions from the keyboard.
    \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.2 Toggle select key.** A toggle type of select key should be
    available as a standard feature or as an option. \[Source: Casali,
    1992\]

**Discussion.** People with disabilities may have difficulty
simultaneously holding a select button down and moving the device, for
example, in \"dragging\" an object in a graphical display. \[Source:
Casali, 1992\]

-   **9.6.3 Avoiding inadvertent operation.** A computer or computer
    system intended to be operable by people with moderate motor
    disabilities should provide either a means for delaying the
    acceptance of a keystroke for a preset, adjustable amount of time or
    a keyguard or means for mounting a keyguard. \[Source: Scadden &
    Vanderheiden, 1988\]

**Definition.** A **keyguard** is a keyboard cover with holes over keys.
\[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.4 Keyguards.** Keyboards should be designed so that keyguards
    can be mounted easily. \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.5 Connection point for alternative input device.** A computer
    or computer system should provide a point at which an alternative
    input device can be connected if modifications cannot be made to
    make a standard input device accessible. \[Source: Scadden &
    Vanderheiden, 1988\]

-   **9.6.6 Input from alternative device.** The computer should treat
    input from an alternative device the same as input from standard
    input devices. \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.7 Readability of lettering on keys and controls.** The
    lettering on keys and controls required for the operation of a
    computer or computer system should be large enough to be read easily
    and have a distinct contrast with its background. \[Source: Scadden
    & Vanderheiden, 1988\]

**Discussion.** This might be accomplished by providing keycaps that can
be removed easily and replaced with special keycaps for the visually
impaired. \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.8 Alternatives to input devices.** When an input device
    necessary for computer operation requires continuous visual feedback
    for operation, an alternate method should be provided for
    accomplishing as many of the functions as possible. \[Source:
    Scadden & Vanderheiden, 1988\]

**Discussion.** It may not be possible to provide a reasonable
alternative for some functions. For example, inputs such as free hand
sketching cannot be done easily without a device that requires eye-hand
coordination. \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.9 Non-visual indication of state of toggle keys.** A computer
    or computer system should provide blind users with a non-visual
    indication of the state of toggle keys that is available
    automatically or upon the user\'s request. \[Source: Scadden &
    Vanderheiden, 1988\]

-   **9.6.10 Key demarcation.** All keys should have edges that can be
    discerned by touch. \[Source: Scadden & Vanderheiden, 1988\]

**Discussion.** In particular, flat membrane keys without ridges
outlining the keys are particularly difficult. \[Source: Scadden &
Vanderheiden, 1988\]

-   **9.6.11 Identification of \"home\" keys.** The \"home\" keys of
    keyboards and keypads should have a distinct marking that can be
    discerned by touch. \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.12 Key labels.** Alternatives to visual key labeling should be
    made available for visually impaired users. \[Source: Scadden &
    Vanderheiden, 1988\]

-   **9.6.13 Special display window.** A windowing environment should
    provide the capability of opening and maintaining a special window
    that can remain fully visible and available continuously for use by
    special input routines. \[Source: Scadden & Vanderheiden, 1988\]

-   **9.6.14 Connection point for switches.** Computers and computing
    systems should provide a point at which at least two momentary
    contact input switches could be connected. \[Source: Scadden &
    Vanderheiden, 1988\]

-   **9.6.15 Distinguishing macro input from typed input.** Computers
    and computing systems should be able to distinguish between typed,
    auto-repeat, and macro-generated \"keystrokes\". \[Source: Scadden &
    Vanderheiden, 1988\]

**Discussion.** \"Keystrokes\" generated by assistive devices or
assistive software may be sent faster than the application software can
recognize them, in which case, they may be ignored, thus preventing use
of the assistive device or software. \[Source: Scadden & Vanderheiden,
1988\]

[]{#__RefHeading___Toc30292683 .anchor}Glossary

**Alphanumeric keys** - The letters of the alphabet, numerals, and
punctuation symbols (numeric keypads may be separate on portable
computers).

**Dedicated formatting keys** - Keys for text formatting operations such
as a **Space** bar, a **Tab** key, and a **Return** or **Enter** key.

**Displacement joystick** - A displacement joystick is a joystick that
moves in the direction it is pushed. Displacement joysticks are usually
spring-loaded so that they return to their center position.

**Fixed-function key** - Keys provided for extra or general functions,
typically labeled **F1, F2,** and so on.

**Hotspot** - The precise part of a screen pointer that marks the screen
position where an operation on a pointing device will have an effect.

**Isometric joystick** - An isometric joystick responds to the amount
and direction of pressure applied to it, but it does not move.
Displacement joysticks usually require less force than isometric
joysticks and are thus less fatiguing over long operating periods.

**Keyguard** - A keyboard cover with holes over keys.

**Menu function** - Causes the appearance of a menu appropriate to the
location of the pointer.

**Modifier keys** - Keys that modify or qualify the effects of other
keys for as long as they are held down, for example, **Shift, Ctrl,**
and **Alt.**

**Navigation keys** - Keys that move a cursor, for example, **Arrow**
keys, **Home, End, Page Up,** and **Page Down.**

**Pointer** - A symbol displayed on the screen that is controlled by a
pointing device. Its shape may change depending on the function that is
invoked at a particular moment or its location on the screen.

**Pointing device** - A non-keyboard device that allows a user to
navigate rapidly around the screen and to specify and select objects for
manipulation and action. Examples include a mouse, trackball, stylus and
grid, and light pen.

**Select function** - Selects or activates objects on the screen or sets
the location of the cursor.

**Special purpose keys** - Keys that have a special function, such as
**Help, Delete,** and **Backspace.**

[]{#__RefHeading___Toc30292684 .anchor}References

American National Standards Institute. (1988). *American national
standard for human factors engineering of visual display terminal
workstations* (ANSI/HFS Standard No. 100). Santa Monica, CA: The Human
Factors Society, Inc. <http://www.ansi.org/>

Avery, L. W., & Bowser, S. E. (Eds.). (1992). Department of Defense
human-computer interface *style guide (Version 2.0,* DOE HFDG ATCCS V2.0
also known as DOD HCISG V2). Washington, DC: Defense Information Systems
Agency.

Casali, S. P. (1992). Cursor control device use by persons with physical
disabilities: Implications for hardware and software design. In
*Proceedings of the Human Factors Society 36th Annual Meeting.* Santa
Monica, CA: Human Factors and Ergonomics Society, 311-315.

Department of Defense. (1987). *User/computer interface* (MIL-STD-1801).
Philadelphia, PA: Navy Publishing and Printing Office.

Department of Defense. (1989). *Human engineering design criteria for
military systems, equipment and facilities* (MIL-STD-1472D).
Philadelphia, PA: Navy Publishing and Printing Office.

Department of Defense. (1999). *Design criteria standard -- Human
engineering* (MIL-STD-1472F). Philadelphia, PA: Navy Publishing and
Printing Office.

Department of Energy. (1992). *Human factors engineering design
criteria* (DOE-HFAC1). Washington, DC: United States Department of
Energy.

Department of the Navy. (1992). *User interface specifications for Navy
command and control systems (Version 1.2,* DON UISNCCS). San Diego, CA:
NCCOSC, RDT&E Division.

Keane, J. (1992). *Human computer interface style guide (Version 1.0)*
(DISA HCISG). Washington, DC: Defense Information Systems Agency.

National Aeronautics and Space Administration. (1989). *Man-systems
integration standards* (NASA-STD-3000A). Houston, TX: National
Aeronautics and Space Administration.

Nuclear Regulatory Commission. (1996). *Human-system interface design
review guidelines* (NUREG-0700). Washington, DC: United States Nuclear
Regulatory Commission.

Scadden, L. A., & Vanderheiden, G. C. (1988). *Considerations in the
design of computers and operating systems to increase their
accessibility to persons with disabilities.* Madison, WI: Trace Research
and Development Center.

[]{#__RefHeading___Toc30292685 .anchor}Index

A

Accommodating people with disabilities 9-26

Alternative input devices 9-21

B

Ball controls 9-14

Ball tracker 9-14

Button functions 9-21

Button operations 9-20

C

Cursor control

key layout 9-5

two-dimensional 9-5

F

Fixed-function keys 9-6

G

Grid 9-17

H

Hotspot 9-20

I

Inadvertent operation 9-26

Input devices

interchangeability 9-25

J

Joy ball 9-14

Joystick 9-1, 9-8

Joysticks 9-10, 9-11, 9-13, 9-14

finger operated displacement 9-11

hand-operated isometric 9-13

mounting 9-14

thumb tip and finger operated 9-13

K

Key

size 9-5

spacing 9-5

Keyboard 9-5, 9-6

feedback 9-6

Keyboard equivalents

to function keys 9-6

to pointing device operations 9-6

Keyboards 9-4

Keyguard 9-26

L

Left-right reversal 9-21

Light pen 9-2, 9-8, 9-16

Limb support 9-15

M

Mouse 9-1, 9-8, 9-9

N

Non-keyboard input devices

advantages 9-1

disadvantages 9-1

O

Optical character recognition 9-22

P

Pointer 9-7

Pointer shapes 9-18, 9-20

Pointing device buttons 9-20

Pointing devices 9-7

R

Rolling ball 9-14

S

Stylus 9-3, 9-8, 9-17

T

TIDs 9-22

Touch interactive devices 9-22

Touch panel 9-22

Touch panels 9-22

Touch screen 9-3, 9-22

Track ball 9-14

Trackball 9-1, 9-8, 9-10

V

Voice activation 9-3

Voice control 9-25

Voice input 9-22