Glossary

**Abbreviation** - Any shortened form or abridgment of a word,
expression, or phrase used to conserve space or time including
initializations, contractions and acronyms.

**Abduction** - Movement away from the midline of the body.

**Accelerators** - Keyboard commands that can be used instead of
pointing and clicking on menu options. They are indicated by underlining
the proper character and placing the keyboard alternative in parenthesis
after the option (e.g., [B]{.underline}old (Ctrl+B)).

**Accreditation** - The authorization and approval granted to an AIS or
network to process sensitive data in an operational environment.

**Acronym** - A word formed from the initial letter or letters of a
group of words.

**Action level** - An 8-hour time-weighted-average noise level of 85 dBA
or, equivalently, a noise dose of 50 percent, at which affected users
will be provided hearing protection and placed in an audiometric testing
program.

**Action statement** - An action verb followed by the object or item
acted upon.

**Active Help** **-** A form of "Help" that senses an inappropriate
entry and interrupts the task to ask users what they are attempting and
if they are sure they want to complete the operation they have just
initiated. Depending upon the user's response to the question, active
"Help" then suggests the correct action.

**Adaptive automation** - Is the real time allocation of tasks to the
user or automated system in a flexible manner, changing the automation
to meet current situational demands. Adaptive automation may benefit
user performance by allowing the user to remain in active control of the
system instead of becoming a passive observer.

**Adduction** - Movement toward the midline.

**Advance organizer** - Supplementary information that is presented
prior to the main body of information in which a user is interested.

**Advice** - An interactive, context-sensitive "Help" source that
indicates what entry to make at the current location in the application,
the required keystroke(s), or which steps to take to complete the task.

**Advisory** - A signal that indicates a safe or normal configuration,
condition of performance, or operation of essential equipment, or
attracts attention and imparts information for routine action purposes.

**Alarm** **filtering** - A technique by which unnecessary alarms are
eliminated.

**Alarm suppression** - Alarm messages are not displayed but are
available to the user upon request.

**Alert** - A signal that indicates a condition relating to the
effective performance of duties. The condition or message requires the
operator or maintainer to take immediate action or indicate that a
significant update in information necessary for the effective
performance of duties is available.

**Alert boxes** - Applied to display messages to users to inform them of
situations that may require their attention or are possibly dangerous.

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

**Anthropometry** - The scientific measurement and collection of data
about human physical characteristics and the application (engineering
anthropometry) of these data in the design and evaluation of systems,
equipment, manufactured products, human- made environments, and
facilities. Biomechanics describes the mechanical characteristics of
biological systems, in this case the human body, in terms of physical
measures and mechanical models. This field is interdisciplinary (mainly
anthropometry, mechanics, physiology, and engineering). Its applications
address mechanical structure, strength, and mobility of humans for
engineering purposes.

**Appendix** - A body of supplementary information collected, labeled,
and placed at the end of a document.

**Attributes** - Instructions that change the characteristics of a
selected item. An example of an attribute is changing text from standard
to bold type.

**Authentication** - The act of identifying and confirming the
eligibility of a station, originator, or user to access specific
categories of information. Authentication is a measure designed to
provide protection against fraudulent entry or transmissions by
establishing the validity of a transmission, message, station, or
originator.

**Authorization** - Granting to a user or user group, the right of
access to a program, a process, or information.

**Automatic test equipment** - Checks two or more signals in sequence
without the intervention of a maintainer. The test usually stops when
the first out-of-tolerance signal is detected.

**Automation** - A device or system that independently carries out a
task that was formerly carried out by a human.

**Automation bias** - When users rely on automated decision aids in a
heuristic manner.

**Biomechanics -** Describes the mechanical characteristics of
biological systems, in this case the human body, in terms of physical
measures and mechanical models.

**Brightness** - An attribute of visual sensation that is determined by
the intensity of light radiation reaching the eye.

**Browse back** - The action of moving to the previous window without
permanently resetting system variables; however, system variables in the
temporary state table will be reset.

**Browse exit** - The action of leaving browse mode.

**Browse next** - The action of moving to the succeeding window without
permanently setting system variables; however, system variables will be
set to a temporary state table.

**Built-in test equipment** - An integral part of a unit of equipment,
can range from a simple voltmeter to a complex automatic checker.

**Cable** - A number of lines bound together within a single, permanent
sheath.

**Cascading menu** - A type of hierarchical menu in which a submenu is
attached to the right side of a menu item. Cascading menus can be added
to drop-down menus, pop-up menus, or even other cascading menus.

**Case** - The part of a unit of equipment that encloses and protects
the equipment from its surroundings. It may also serve to protect the
surroundings - including maintainers - from the equipment.

**Cathode Ray Tube** **(CRT)** - A vacuum tube of a television or
computer monitor in which the inner surface is coated with phosphors
which glow and produce light when hit by an electron beam. CRT is often
used as a generic term for a computer monitor.

**Caution** - A signal that indicates the existence of a condition
requiring attention but not immediate action or a written notice given
when a situation might result in damage to, or destruction of, equipment
or systems.

**Center-justified text** - Lines are centered on the page, with both
right and left margins ragged.

**Central visual field** - Central visual field (sometimes referred to
as the focal area) is the central 30° of the visual field. This is the
area that people use to look at objects in the world, moving their eyes
as needed to bring images of the object onto the fovea, which is the
area of highest acuity. When an object is outside of the focal area, a
person will usually turn their head rather than simply move their eyes.

**Certification** - The technical evaluation that supports the
accreditation process and establishes the extent to which a particular
computer system or network design and implementation meets a
pre-specified set of security requirements.

**Circumduction** - A continuous circular movement of a limb.

**Client area (or working area)** - The main area of the window that
users employ to do their operational or application tasks. It is the
area where users make their inputs and receive their outputs.

**Collating test** **equipment** - Presents the results of two or more
checks as a single display; for example, a light might come on only if a
number of different signals are in tolerance.

**Color fringes** - Are the pixels along the border of an object that
contain a combination of the selection and background colors.

**Combo box** - A special type of text box with an attached list of
options. Combo boxes allow the user to either select from the given list
or type in an alternative response. There are two types of combo boxes,
standard and drop-down.

**Comfort zone** - That range of environmental conditions in which
humans can achieve thermal comfort. It is affected by work rate,
clothing, and state of acclimatization.

**Command entries** - A type of control entry that enables the user to
initiate a message to the system that will specify desired functions.

**Command language** - A limited programming language used strictly for
executing a series of commands (e.g., Linux, any DOS shells).

**Commands** - Instructions that cause a device to perform some action.

**Component -** A subdivision of a unit of equipment that can be treated
as an object by the maintainer, but which can be further broken down
into parts. A mounting board together with its mounted parts is an
example of a component.

**Connector** - A piece of hardware that joins or attaches lines or
cables to other lines or cables or to units of equipment. The term is
used rather loosely to refer to either of the two parts that mate with
each other and to the plug that mates with a receptacle.

**Consistency** - Consistent means adhering to the same principles with
minimal variation.

**Contrast** - The range between the lightest tones and the darkest
tones. The lower the number value, the more closely the shades will
resemble each other. The higher the number, the more the shades will
stand out from each other.

**Contrast ratio** - The luminance of the foreground divided by the
luminance of the background. It indicates how much brighter a pure white
output would be than a pure black output. The greater the contrast, the
sharper the image will be. It is also called luminance ratio.

**Control automation** - When an automated system executes actions or
control tasks with some level of autonomy.

**Control entries** - User input for sequence control, such as function
key activation, menu selection, and command entry.

**Copy** - Instructs the computer to copy selected data.

**Correlation coefficient or \"r\" value** - Describes the degree to
which two variables vary together (positive correlation) or vary
inversely (negative correlation). The correlation coefficient, \"r\",
has a range of values from +1.0 (perfect positive correlation) through
-1.0 (perfect negative correlation). Multiple correlation involves the
predictable relationship of two or more variables with another criterion
variable (such as a composite measurement value).

**Corridors** - Walkways that are physically restricted by walls or the
like.

**Cover** - A part of a unit of equipment that closes an access opening.

**Critical** **function** - Is a function that can cause system failure
when a malfunction is not attended to immediately.

**CRT** - See Cathode Ray Tube.

**Cursor** - A marker on the display screen that indicates the position
where the computer expects the next input or will display the next
output. The cursor may be positioned by the computer or by the user.

**Dark adaptation** - The process by which the eyes become more
sensitive in dim light. The eyes adapt almost completely in about 30
minutes, but the time required for dark adaptation depends on the color,
duration of exposure and intensity of the previous light.

**Database** - A set of interrelated data stored in a computer.

**Data-entry window** - A window that contains a set of labeled fields
for entering, changing, and deleting data. It may also contain labeled
data display fields, which a user cannot change.

**Decision aids** - (sometimes referred to as decision support systems)
Automated systems that provide support to human decision-making
processes, either unsolicited or by user request. Decision aids can
narrow the decision alternatives to a few or suggest a preferred
decision based on available data.

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

**Depression** - The lowering of a body member from its normal position.

**Design limits approach** - A method of applying population or sample
statistics and data about human physical characteristics to a design so
that a desired portion of the user population is accommodated by the
design. The range of users accommodated is a function of limits used in
setting the population portion.

**Diffuse glare -** A type of glare caused by the general ambient
luminance, which effectively reduces the display contrast without
producing significant specular reflection.

**Direct manipulation** - When the user controls the interaction with
the computer by acting directly on objects on the display screen. An
object may be an icon, menu option, symbol, button, or dialog box. An
example of direct manipulation is a GUI.

**Disability -** A physical or mental impairment that substantially
limits one or more of a person\'s major life activities.

**Disparity** - The computation of depth values based on the lateral
distance between corresponding picture elements in both image planes of
stereo vision.

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

**Display sequencing** - A means of reducing clutter by displaying a
series of partial displays (e.g., a map and a series of overlays) or of
displaying data sequentially. It can also be used as a form of
animation.

**Dose** - The accumulated exposure to noise.

**Drop-down combo box** - A combo box that has a down arrow button, and
a drop-down list.

**Dwell emphasis** - When the pointer comes to rest for a predetermined
time on a selected object, the computer tells the user which object it
perceives the user is about to select.

**Dynamic strength** - A force exerted by limbs moving in a smooth
manner over time, such as while lifting an object.

**Dynamically-generated fault isolation recommendation** - A
recommendation made by a computer system based on stored information and
information received from user inputs, automated system inputs, or both.
The information used by the system may include historical information,
heuristics, probability factors, and cost factors. The recommendation
may be derived using model-based reasoning, dependency models,
fault-based reasoning, rule-based logic, information theory, or advanced
artificial intelligence schema.

**Effective temperature** - An empirical thermal index that illustrates
how combinations of dry bulb air temperature, wet bulb temperature,
velocity of air, and clothing affect people.

**Effective watt** - Equal to 1.84 watts.

**Effectively** - Carrying out a task effectively means producing the
desired result.

**Efficiently** - Carrying out a task efficiently means that the desired
result is produced with a minimum of waste (usually in relation to
time).

**ELD** - See electroluminescent displays.

**Electroluminescent displays (ELD)** - A flat-panel display, the type
typically used for laptop computers, that works by placing a thin
phosphorescent film between one plate coated with vertical wires and
another plate with horizontal wires, to form a grid. When an electrical
current passes through a horizontal and a vertical wire, the
phosphorescent film at this intersection glows, creating a point of
light (pixel).

**Elevation** - The raising of a body member from a normal position.

**Ellipses** - Visual indicators, such as three dots (\...), used to
distinguish menu options that branch to other sub-menus, from menu
options that will immediately perform an operation.

**Exclusive buttons** (option buttons or radio buttons) - Single,
two-state choices, which are mutually exclusive from each other.

**Explosive strength** - The application of peak amounts of strength for
short periods of time, usually periodically, such as in running or
sprinting.

**Extension** - The straightening of a limb or an increase in the angle
between parts of the body.

**Fasteners** - Devices that join, attach, and mount parts, components,
cases, covers, and units of equipment. They include quick fastening and
releasing devices, screws, bolts, latches, catches, rivets, retainer
rings, and retainer chains.

**Figure** - An exhibit that is primarily graphical or pictorial in
nature, as opposed to verbal or numerical.

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

**Flexion** - The process of bending a limb or decreasing the angle
between parts of the body.

**Flicker -** The appearance of flashing that occurs in a computer
display when the display is not refreshed frequently enough causing the
phosphor to begin to decay prior to being refreshed.

**Focal vision** - The central 30° of the visual field. It is the area
that people use to look at objects in the world, moving their eyes as
needed to bring images of the object on to the fovea, which is the area
of highest acuity.

**Foot lamberts** - Is a measure that has been corrected for the visual
system's differential sensitivity to different wavelengths, giving an
approximation to perceived brightness.

**Fovea** - The small central region of the retina that exhibits the
greatest sensitivity to detail and color.

**Fully-justified text** - Spacing is added within and between words so
that all lines are the same length, resulting in alignment of both right
and left margins.

**Function keys** - Labeled keys that serve as keyboard short cuts
(e.g., F1, F2, F3, or with the function name such as Delete or Insert)
by combining in one key the actions of a sequence of individual keys.

**Gas plasma display** - Is a type of flat-panel display that works by
placing neon gas between one plate coated with vertical conductive print
and another plate coated with horizontal conductive print to form a
grid. A point of light (pixel) is created at the intersection of a
horizontal and vertical line that has been charged with an electric
current.

**Glare** - Is produced by any luminance within the visual field that is
sufficiently greater than the luminance to which the eye is adjusted.
Glare causes eye fatigue, discomfort, and annoyance, as well as
interfering with visual performance and visibility.

**Go, no-go test equipment** - Provides one of two alternative answers
to any question. For example, it tells whether a given signal is in or
out of tolerance.

**Graphic menus** (palettes) - A set of unlabeled symbols, typically
presented within small rectangles. Symbols may be icons, patterns,
characters, or drawings that represent an operation. Palettes are used
widely in drawing and painting packages but are commonly found in
word-processing applications as well.

**Grid lines** - Horizontal lines, vertical lines, or both, extending
from the scale divisions of one or both axes of a graph and intended to
aid users in locating and reading data points.

**Group** - On a pull-down menu, a group is any set of menu items
between two separators or the whole list if there are no separators on
the pull-down menu.

**Guard** - An enclosure or barrier intended to prevent inadvertent or
unauthorized operation of a control.

**Hard function key** - The physical function key on the keyboard.

**Hazardous condition** - The presence of energy or a substance which is
likely to cause death or injury by reason of physical force, shock,
radiation, explosion, flames, poison, corrosion, oxidation, irritation,
or other debilitation. Biological and chemical hazards can have
debilitating effects through disease or interference with physiological
functions.

**Hazardous location** - A space within a facility, room, or open
environment where a hazardous condition exists or is accessible or
exposed within the system or equipment located within the space.

**Heading** - The title of an organizational subdivision of a document,
that is, a title that has hierarchical significance.

**Hierarchical menu** - A large series of options or menus that is
organized as a multi-level, branching structure in which an option in a
higher-level menu is the name of another menu at the next lower level.
The options in the lowest level menus are not the names of other menus.
They are commands or selectable values, such as color squares on a
palette or specific Auto Text choices (e.g., Dear Sir, or To Whom It May
Concern).

**Hot spot** - The selectable area in which a user can place the pointer
and successfully select an icon.

**Human physical and associated measurement characteristics** - Refers
to specific physical, mobility, or strength features of human users and
to the explicit way that a human feature or capability is measured for
use as general anthropometric or biomechanics data or as data for a
specific design.

**Identification** - The process that enables the security safeguards to
recognize a user name (usually through a machine-readable name) as an
identical match to a name previously listed in an authorized user file.

**Illumination** - The amount of light (luminance flux) falling on a
surface. Measured in lumen/m2 = lux = 0.093 ft-c. Illumination decreases
with the square of the distance from a point source.

**Impairment** - A loss or abnormality of physiological or anatomical
structure or function.

**Indication statement** - States the name of an indicator that the user
reads or observes and the indication expected to result from the action.

**Information automation** - Includes information acquisition and
integration. This type of automation would include filtering,
distributing or transforming data, providing confidence estimates and
integrity checks, and enabling user requests

**Input focus** - The notion that only one window and usually only one
object in a window at a time is capable of accepting input from a
pointing device or the keyboard.

**Interlaced** - A display that produces a video image by displaying
alternate scan lines.

**Interlocks** - Devices (for example, switches) connected with a cover,
shield, or case that disable the associated internal hazard (usually
electrical) when the cover, shield, or case is opened. OSHA regulations
discuss lockout and tagout procedures to be used in the workplace during
maintenance or operations to protect from electrical hazards.

**Interocular crosstalk** - When the left eye can see the images
intended for the right eye, and vice versa.

**Irradiance** - The radiant flux density on a given surface.

**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.

**Item** - A nonspecific term used to denote any product, available or
in design or development, including parts, components, modules, and
units of equipment.

**Jitter** - A departure from geometric stability which occurs when
pixels in displayed objects move instead of remaining in a fixed
position.

**Keyboard accelerator** - A key or simultaneous combination of keys
that a user can type to select an option in a menu without having to
display the menu.

**Keyboard lockout** - A state determined by an application in which the
application does not accept input from the keyboard.

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

**Label -** Alphanumeric information that identifies or describes an
object. Labels can be printed directly on or adjacent to the object, or
they can be printed on a card or plate that is attached to the object or
adjacent to the object.

**Lateral rotation -** Turning away from the midline of the body.

**Layout -** The physical arrangement of the parts and components that
make up a module or a unit of equipment.

**LCD** **-** See liquid crystal display.

**Left-justified text -** Lines of text are aligned at the left, but
spacing within and between words is not varied, resulting in a ragged
right margin.

**Legibility -** The extent to which the user can decipher or read
alphanumeric characters or text.

**Levers** - Controls having the same size and shape, but that allow
continuous adjustment.

**Limit stops** - Mechanical mechanisms designed to restrict a moving
object or part by stopping it at predetermined (limit) positions.

**Line -** Any single length of pipe, wire, or tubing.

**Linking sentence -** A sentence that connects the paragraph it is in
to the paragraph that precedes or follows it. The connection is usually
accomplished by repeating a word or phrase or referring to a concept.

**Liquid crystal display (LCD) -** Is a flat-panel display that works by
suspending liquid crystals between two transparent sheets of polarizing
material. An electric current passes through the liquid causing the
crystals to act like a shutter, either permitting light to pass through
or blocking the light so that it cannot pass through.

**List -** A series of similar or related items in which each item is
marked and displayed on a separate line or lines. The markings can be
graphic symbols, such as bullets () or squares (), or sequential
identifiers, such as numbers or letters. An item can be a word, a
phrase, a sentence, or a group of sentences.

**Lockout -** Uses a mechanical mean to disable a control or switch in
its safe position (for example, electricity disconnected) and to prevent
its activation without the use of undue force or tools.

**Luminance -** The amount of light per unit area emitted or reflected
from a surface. Measured in candela per square meter (cd/m2 ),
footlamberts (ft-L), or millilamberts (mL). 1.0 cd/m2 = 0.31 mL = 0.29
ft-L. The luminance of a surface does not vary with the distance of the
observer from the surface being viewed. Luminance is expressed in
candela per meter squared or foot lamberts.

**Luminance contrast** - The contrast between a figure and its
background.

**Luminance ratio -** The luminance of the foreground divided by the
luminance of the background. It indicates how much brighter a pure white
output would be than a pure black output. The greater the contrast, the
sharper the image will be. It is also called contrast ratio.

**Marking -** Nonverbal information, such as colors or symbols, that
identifies or describes an object. Marking can appear directly on or
adjacent to the object, or it can be printed on a card or plate that is
attached to the object or adjacent to the object.

**Mechanical binding -** The pages are punched with either round or
slotted holes and then placed in a ring binder or bound with a comb or
spiral binder.

**Medial rotation -** Turning toward the midline of the body.

**Mental model** - An individual's understanding of the processes
underlying system operation.

**Menu** - A list of options from which a user makes a selection or
selections.

**Menu bar** - A narrow panel, usually at the top of a computer screen
in menu-based computer systems, that continually displays the
highest-level menu options for selection by the user. The options on a
menu bar are usually the names of other menus**.**

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

**Message window** (**message box**) - A secondary window that provides
users with non-critical information, progress information about lengthy
processes, alerts to unusual events, and/or warnings of potential
dangers. Message windows may be modal or modeless.

**Minimize** -- The operation that reduces a windows presence into a
standby icon button on the information line at the bottom of the screen.

**Mnemonic** - A single letter that a user can type to select an option
in a menu.

**Modal window** - A window with which a user must interact before being
able to interact with any other windows. A user cannot interact with
other windows as long as the modal window is displayed.

**Modeless** **window** - A window that allows a user to interact with
other windows.

**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.**

**Modular -** To be modular means to be designed with standardized or
uniform components.

**Modularization -** The separation of equipment into physically and
functionally distinct units that can be easily removed and replaced.

**Module -** An assemblage of two or more interconnected parts or
components that comprise a single physical and functional entity. It is
this singular functionality that defines a module.

**Motion artifacts** - The after images that appear to follow a moving
display object because the images of the previously drawn object have
not yet decayed enough to disappear. They often look like the tail of a
comet following the object in motion.

**Mounting -** The positioning and attachment of parts, components, and
modules.

**N -** Is a metric term for the force measure called a Newton. One
pound force in the English measurement system is equal to 4.4482 Newton
(1 lbf = 4.4482 N).

**Navigation keys** - Keys that move a cursor, for example, **Arrow**
keys, **Home, End, Page Up,** and **Page Down,** which are dedicated to
keyboard navigation

**Newton -** A one pound force in the English measurement system is
equal to 4.4482 Newton (1 lbf = 4.4482 N).

**Non interlaced -** A display that produces a video image by displaying
all lines in a frame in one pass from top to bottom before the next
frame appears.

**Note** - A written notice given to draw the reader\'s attention to
something or to supply additional information.

**On-line Help** - Primarily an interactive, context-sensitive source of
information that can prompt a user what entry to make at the current
location in an application, what keystrokes are required, or what steps
are required to complete a task. Secondarily, on-line Help is a form of
on-line documentation and reference information.

**Option** - One of the selectable items in a menu.

**Option buttons** (exclusive buttons or radio buttons) - Single,
two-state choices, which are mutually exclusive from each other.

**Outline selection** - An extended form of drag selection that is
particularly useful for graphical objects when normal drag selection
conflicts with moving objects with the mouse.

**Packaging** (of a unit of equipment) - The assembling, mounting, and
enclosing of the items it includes.

**Paging** - The process of scrolling through data one page at a time.

**Palettes** (graphic menus) - A set of unlabeled symbols, typically
presented within small rectangles. Symbols may be icons, patterns,
characters, or drawings that represent an operation. Palettes are used
widely in drawing and painting packages but are commonly found in
word-processing applications as well.

**Pamphlet binding -** The pages are stitched or stapled together. There
are two types of pamphlet binding, saddle stitched and side stitched.

**Panes** - The separate viewing areas in a split window.

**Panning** - An orientation of display framing in which a user
conceives of the display frame as moving over a fixed array of data.

**Part -** An object that cannot normally be broken down further without
destroying its designated use. Fuses, resistors, and capacitors are
examples of parts.

**Passageways** - Areas across which people must pass for work purposes.

**Passive Help** - A form of Help that simply responds to user requests
for information. The information may be in the form of on-line system
documentation, such as a user\'s guide or a list of functions performed
by combinations of key presses.

**Percentile statistic -** Determined by ranking all data values (using
the applicable measurement values related to the selected human physical
characteristic) in the sample and determining the percentage of data
that fall at or below a specific datum value.

**Percentile value** **(or point) of the selected datum** - The
percentage of data that fall at or below a specific datum value.

**Perfect binding** - The pages are assembled, the left side is cut and
roughed, glue is applied, and the cover is attached to the pages.

**Phosphor** - A luminescent substance, used to coat the inside of a
CRT, which emits visible light when illuminated by electrons within an
evacuated glass tube.

**Pica -** The unit of measurement used in printing. It is equal to 0.17
inch (4.23 mm).

**Point** - A measure of the height of type; there are 72 points in an
inch (2.54 cm).

**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.

**Polarity -** The relationship between the brightness of the background
and an image. Bright images on a dark background is negative polarity
and dark images on a bright background is positive polarity.

**Pop-up** **menus** - Menus that only appear on user demand. They are
often associated with a particular object on a display (e.g., a pop-up
menu listing acceptable command options close to the immediate work
area). Because pop-up menus are not displayed all of the time, they do
not take up valuable screen space. They provide an efficient way to
access commands because they eliminate the need for the user to navigate
to a menu bar or control bar. A pop-up menu typically contains 5 to 10
options presented in a vertical listing.

**Predefined fault isolation sequence -** A sequence of fixed procedures
and tests that leads to a suspected fault. It is similar to a fault tree
in a fault isolation manual.

**Preferred speech interference level (PSIL-4) -** A measure of the
effectiveness of noise in masking speech.

**Primary colors -** Are Red, Green, and Blue (RGB) for light emitting
displays such as CRTs. This is different than the primary colors for
subtractive color mixture (like mixing paints), which are Yellow, Red
and Blue.

**Primary window** - A top or high-level window in an application. It is
the main location of user interaction and functions independent of other
primary windows in the application.

**Print contrast** - The ratio of the difference in brightness between
the printing and its background to the brightness of the background
(assuming dark print on a light background). It is defined by
(B1-B2)/B1, where B1 is the brighter of the two.

**Proceduralized instruction** - A set of step-by-step instructions for
a procedure intended to ensure the successful completion of a task.

**Pronation** - The downward turning of the palm.

**Public entrances** - Any entrances that are not loading or service
entrances.

**Pull-down menu** - A menu associated with an option on a menu bar that
appears when a menu bar option is selected.

**Query** - The process of specifying, locating, and retrieving data
matching specified characteristics from a database.

**\"R,\" The multiple correlation coefficient** **-** Is a statistical
number that indicates the strength of the relationship between sets of
data. The correlation coefficient can be between --1 and +1 with a
correlation of \|1\| indicating a perfect correlation. The closer the
number is to \|1\|, the stronger the relationship between the two sets
of data. It is recommended that only correlations with strong predictive
values be used (that is where r or R is at least or greater than
\|.7\|).

**Radio buttons** (exclusive buttons or option buttons) - Single,
two-state choices, which are mutually exclusive from each other.

**Reasonable accommodation** - Any modification or adjustment to a job
or the work environment that will enable a qualified person with a
disability to participate in the application process and to perform
essential job functions.

**Reflectance** - The ratio of luminous flux reflected from a surface to
luminous flux striking it.

**Refresh rate** - The rate (in cycles per second or Hz) at which the
displayed contents of a computer screen are regenerated.

**Resolution** - The number of pixel elements per square inch on a
monitor.

**Right hand page/Left hand page -** The terms right-hand page and
left-hand page have meaning only if pages are printed on both sides. In
that case, a right-hand page is the page printed on the front, and a
left-hand page is the page printed on the back. Thus, when the pages are
bound, and the document is open, the right-hand page appears on the
right, and the left-hand page appears on the left.

**Right-justified text** - Lines of text are aligned at the right, but
spacing within and between words is not varied, resulting in a ragged
left margin.

**Saddle stitching -** A type of pamphlet binding that permits the
document to lie flat.

**Saturation** - The relative amount of whiteness in a chromatic color.

**Save** - A command that causes the computer to save the data.

**Scrolling** - A method used to move through the contents of a window
or list in a dialogue box using the scroll-bar or scroll arrows.

**Scrolling menu** - A menu, usually containing many options, that does
not display all of the options at once. It includes a scroll-bar that
permits the sequential display of all options. Scrolling menus are also
called list boxes and scrolling lists.

**Seat reference point** - A point in the mid-sagittal plane where the
seat back and seat pan intersect.

**Secondary colors -** Secondary colors are Cyan, Magenta, and Yellow
(CMY) for light emitting displays such as CRTs.

**Secondary window** - A window that is displayed from within a primary
window or another secondary window. Secondary windows are sometimes
called child windows.

**Security architecture** - A subset of the overall system architecture
that protects the automated system, telecommunication, physical, and
informational assets through denial of service and unauthorized
(accidental or intentional) disclosure, modification, or destruction.

**Security safeguards** - The protective measures and controls that are
prescribed to meet the security requirements specified for a system.
Those safeguards may include but are not necessarily limited to:
operational procedures, physical security, or hardware and software
features.

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

**Selection** - The action a user makes in choosing a menu option.
Selection may be accomplished by pointing, by typing, or by pressing a
function key.

**Serifs** - Decorative elements (short lines, knobs, and balls) at the
ends of the strokes that form letters. Sans serif fonts do not have
these decorative elements.

**Service points** - A means for lubricating, filling, draining,
charging, and performing other service functions. They permit the
routine performance of these services on all equipment and components
requiring them.

**Shield** - An enclosure or barrier intended to protect components that
are susceptible to damage or to protect maintainers from possible
injury.

**Slider** - A control used to set a value and give a visual indication
of the setting.

**Soft function key** - An area on the screen that represents a function
key.

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

**Specular glare -** The appearance of unwanted images (reflections) on
the display surface.

**Specular surface** - One that provides a specular reflection, a shiny
surface.

**Speech interference level** **(SIL or SIL-4)** - A measure of the
effectiveness of noise in masking speech. It is the arithmetic mean of
the same pressure levels of interfering noise in the four octave bands
centered on the frequencies 500, 1000, 2000, and 4000 Hz, respectively.
The unit of speech interference is the decibel (dB).

**Spin box** (also known as a **spin button**) - A variation of the
scrolling menu or list. A spin box is made up of a text box and two
arrows and displays a sequence of mutually exclusive choices.

**Spin button** (also known as a **spin box**) - A variation of the
scrolling menu or list. A spin button is made up of a text box and two
arrows and displays a sequence of mutually exclusive choices.

**Split bar** - The divider placed across the middle of the window that
separates the panes.

**Split box** - A rectangular indicator located inside the scroll-bar of
a split window or immediately above the scroll-bar of a split-able
window. Note, however, that in some rules, the split box is called the
split bar.

**Stacking** - The stringing together of commands so that they can all
be executed with a single command.

**Standard combo boxes** - A special type of text box that includes a
standard list of options with all options visible to the user.

**Standardization** - Standardization refers to common user-interface
features across multiple applications.

**Stated indication -** What is expected if the equipment or system is
operating normally.

**Static strength -** Also known as isometric strength, which is steady
force exerted while the limbs are in a stationary or static position.

**Status bar** - A special type of message bar used to present
information about the current status of the application.

**Stereopsis** (also called **stereoscopic vision**) - Three-dimensional
depth perception based on retinal disparity. As the eyes are slightly
separated, each eye sees a slightly different image, when these images
are fused in the brain. The result is a perception of depth or
stereoscopic vision.

**Stereoscopic display** **-** A method used to generate the sensation
of three dimensions within the human visual system. Three-dimensional
display technology may be \"stereoscopic,\" which requires that users
wear special glasses that provide different images to the two eyes, or
\"auto stereoscopic,\" which does not require any special viewing aids.

**Stereoscopic vision** **-** See Stereopsis.

**Stroke width** - The thickness of the lines used to make up the number
or letter.

**Supination** - Is the upward turning of the palm, or lying face up.

**Syntax** - The set of rules governing the language of a command
language. Examples would be rules about the order in which parts of a
command occur or rules about punctuation in commands.

**Table** - An array of data or text in rows and columns. Usually at
least one dimension, either the rows or the columns, is labeled;
sometimes both are labeled.

**Tagouts** - Tags that are attached to a control or place of hazard to
identify the required control condition and hazard associated with an
ongoing mode of operation or maintenance.

**Tailoring** - The process of selecting and evaluating individual
standards to determine the extent to which they apply to a specific
system or piece of equipment. It includes the process of modifying these
standards to ensure that there is an optimal balance between operational
needs and cost.

**Tear-off menu** - A menu that can be removed from the menu bar and
moved to another location on the screen where it can remain on display.
Tear-off menus are also called "tacked" or "pushpin" menus.

**Technical Issuances** - According to FAA Order 1320.1D, are
publications acquired from non-agency sources or developed within FAA
that directly concern installation, maintenance, or modification of
equipment, equipment systems, facilities, or aircraft. Manufacturers\'
instruction books for plants and equipment are included in this
category. A basic objective of using this category is to permit the
merging of internally-developed and externally-acquired technical
manuals and publications into consolidated, single source documents.
Because of necessary deviations from standard directive format and
issuance procedures, they are designated technical issuances.

**Test points -** A means for conveniently and safely determining the
operational status of equipment and for isolating malfunctions.

**Text boxes** - Edit controls into which the user types information.
Most text boxes are one line tall, but applications can also use
multi-line text boxes.

**Text frame** - A sizable field into which the user can type text. This
is a dynamic form of an edit field and should not be confused with the
text box. Although text frames are generally rectangular, other shapes
may also be used.

**Thermal comfort** - Defined as a mental condition that is based upon
the lack of perception of noticeable changes in temperature, and that
results in a personal expression of satisfaction with the environment.

**Title** - A word or phrase that describes or identifies the contents
of a document or a portion of a document.

**Toggle switch** - A switch with discrete positions operated by a
lever.

**Toggled menu options** - Options that are used to issue commands as a
binary selection of one of two opposite commands.

**Tonal coding** - Coding based on different shades of the same hue or
different patterns or textures.

**Transilluminated display** - A display in which light passes through
the element being viewed.

**Tremor** - The oscillation of a body extremity, which may occurring
along with an effort to maintain a fixed position or direction. The
degree of tremor is measured by the distance or number of departures
from the fixed path or position per unit of time. Tremor increases when
(1) effort is made not to tremble, and (2) fatigue is present. It is
greatest in vertical motion, less in front-to-back motion, and least in
side-to-side motion.

**Type family** - A collection of fonts that are similar in design but
vary in size and boldness.

**Unit of equipment** - An assemblage of items that may include modules,
components, and parts that are packaged together into a single hardware
package. For example, a computer, its keyboard, and its visual display
are all units of equipment, as are radio transmitters and receivers.

**User-centered perspective** - A user-centered perspective involves
focusing on the needs and requirements of the end user throughout the
design, acquisition, or development process.

1.  **Utility window** - A supplementary window that provides the users
    with additional tools or controls, such as a tool palette or a set
    of text attributes.

**Viewing angle** - The angle off the center line from which a display
will be viewed.

**Ventilation** - The process of supplying air to or removing air from
any space by natural or mechanical means. From the standpoint of comfort
and health, ventilation issues involve both quantity and quality.

**Visual angle** - The angle subtended by objects measured in minutes of
arc. It represents an apparent size of an object based on the
relationship between an object\'s distance from the viewer and its size
(perpendicular to the viewer\'s line of sight). For example, if an
object that is size ***h*** is at a distance ***d*** from the retina,
the visual angle subtended, ***x***, is: ***x*** = arctan
(***h***/***d***).

**Walkways** - Areas designated for walking.

**Warning** - A written notice given to a reader when a situation might
result in personal injury or loss of life; a caution is a written notice
given when a situation might result in damage to or destruction of
equipment or systems; a note is a written notice given to draw the
reader\'s attention to something or to supply additional information.

**Weighted sound level** **(dB(A))** - A sound pressure level (in
decibels) measured using a sound level meter with an A-weighting
network. The A-weighted response is maximum at 2500 Hz, drops rapidly as
frequency decreases below 1000 Hz, and gradually decreases above 4000
Hz, thereby approximating the frequency dependent human response to
moderate sound levels. ANSI S1.4 gives the definition of a-weighting
filter characteristics.

**Working area (or client area)** - The main area of the window that
users employ to do their operational or application tasks. It is the
area where users make their inputs and receive their outputs.

**Workplaces** - An area, room, or establishment where work is done.

**Workstations** - A place designed for a specific task or activity from
where work is conducted or operations are directed. Desks, offices,
repair benches, tools, equipment, and computer terminals are examples of
these special accommodations and equipment. Workstations are designed as
areas for one or more workers to use in accomplishing purposeful tasks
or jobs.