WindsorLive.com Providing Web Accessible Solutions Windsor Ontario Canada

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Web Accessibility FAQ's

Glossary of Terms

Alphabetical Links

A — Z Index

A
Access: To interact with a system entity in order to manipulate, use, gain knowledge of, and/or obtain a representation of some or all of a system entity's resources.
Accessibility: The art of ensuring that, to as large an extent as possible, facilities (such as, for example, Web access) are available to people whether or not they have impairments of one sort or another.; The set of properties that allows a product, service, or facility to be used by people with a wide range of capabilities, either directly or in conjunction with assistive technologies. Although the term "accessibility" typically addresses users who have a disability, the concept is not limited to disability issues.
Accessibility Awareness: An "accessibility-aware" application is one that has been designed to account for authors' differing needs, abilities, and technologies. In the case of authoring tools, this means that (1) care has been taken to ensure that the content produced by user-authors is accessible and (2) that the user interface has been designed to be usable with a variety of display and control technologies.
Accessibility Information: "Accessibility information" is content, including information and markup, that is used to improve the accessibility of a document. Accessibility information includes, but is not limited to, equivalent alternative information.
Accessibility Problem: Inaccessible Web content or authoring tools cannot be used by some people with disabilities.
Accessible: Content is accessible when it may be used by someone with a disability.
Accessible Authoring Practice: "Accessible authoring practices" improve the accessibility of Web content. Both authors and tools engage in accessible authoring practices.
Access Key: The portion of an option name or control label used for keyboard selection. Also called mnemonic, implicit designator, or menu mnemonic.
Acronym: An identifier formed from some of the letters (often the initials) of a phrase and used as an abbreviation.
Aging-Related Conditions: Changes in people's functional ability due to aging can include subtle and/or gradual changes in abilities or a combination of abilities including vision, hearing, dexterity and memory. Any one of these limitations can affect an individual's ability to access Web content.
Alternative Equivalents: Since rendered content in some forms is not always accessible to users with disabilities, authors must supply alternative equivalents for content. In the context of this document, the equivalent must fulfill essentially the same function for the person with a disability (at least insofar as is feasible, given the nature of the disability and the state of technology), as the "primary" content does for the person without any disability.
Alternative Information: Content is "equivalent" to other content when both fulfill essentially the same function or purpose upon presentation to the user. Equivalent alternatives play an important role in accessible authoring practices since certain types of content may not be accessible to all users (e.g., video, images, audio, etc.). Authors are encouraged to provide text equivalents for non-text content since text may be rendered as synthesized speech for individuals who have visual or learning disabilities, as braille for individuals who are blind, or as graphical text for individuals who are deaf or do not have a disability.
Alternative Keyboards: Alternate keyboards are hardware or software devices used by people with physical disabilities, that provide an alternate way of creating keystrokes that appear to come from the standard keyboard.
Animation: "Animation" refers to any visual movement effect created automatically (i.e., without manual user interaction). This definition of animation includes video and animated images.
Applet: An applet is a program (generally written in the Java programming language) that is part of content, and that the user agent executes.
Array: A set of elements of some type that can be identified by an index, starting in JavaScript at 0, and increasing by 1 for each subsequent member of the array.
Assistive Technology: Any item, piece of equipment, or system, whether acquired commercially, modified, or customized, that is commonly used to increase, maintain, or improve functional capabilities of individuals with disabilities.
Attribute: A distinct characteristic of an object. An object's attributes are said to describe the object. Objects' attributes are often specified in terms of their physical traits, such as size, shape, weight, and colour, etc., for real-world objects. Objects in cyberspace might have attributes describing size, type of encoding, network address, etc. Salient attributes of an object is decided by the beholder.
Audio: "Audio" refers to content that encodes prerecorded sound.
Audio-only presentation: An audio-only presentation is content consisting exclusively of one or more audio tracks presented concurrently or in series. Examples of an audio-only presentation include a musical performance, a radio-style news broadcast, and a narration.
Audio Description, Auditory Description: An audio description or "auditory description", is either a prerecorded human voice or a synthesized voice (recorded or generated dynamically) describing the key visual elements of a movie or other animation. The audio description is synchronized with (and possibly included as part of) the audio track of the presentation, usually during natural pauses in the audio track. Audio descriptions include information about actions, body language, graphics, and scene changes.
Authentication: To positively verify the identity of a user, device, or other entity in a computer system, often as a prerequisite to allowing access to resources in a system.
Authoring Tool: An "authoring tool" is any software that is used to produce content for publishing on the Web.
Author styles: Authors styles are style property values that come from content (e.g., style sheets within a document, that are associated with a document, or that are generated by a server).
B
Backward Compatible: Design that continues to work with earlier versions of a language, program, etc.
Blindness: Blindness involves a substantial, uncorrectable loss of vision in both eyes.
Braille: Braille uses six raised dots in different patterns to represent letters and numbers to be read by people who are blind with their fingertips.
Braille Display: A braille display, commonly referred to as a "dynamic braille display," raises or lowers dot patterns on command from an electronic device, usually a computer. The result is a line of braille that can change from moment to moment. Current dynamic braille displays range in size from one cell (six or eight dots) to an eighty-cell line, most having between twelve and twenty cells per line.
Braille and Refreshable Braille: Braille is a system using six to eight raised dots in various patterns to represent letters and numbers that can be read by the fingertips. Braille systems vary greatly around the world. Some "grades" of braille include additional codes beyond standard alpha-numeric characters to represent common letter groupings (e.g., "th," "ble" in Grade II American English braille) in order to make braille more compact. An 8-dot version of braille has been developed to allow all ASCII characters to be represented. Dynamic or refreshable braille involves the use of a mechanical display where dots (pins) can be raised and lowered dynamically to allow any braille characters to be displayed.
Browser (for Non-Visual Output): Blind and partially sighted people will use one of three possible methods to read pages on the World Wide Web. Users with some sight can use screen magnification software. For users with little or no useful sight the options are Speech Synthesizers or sound card to convert text into speech or a refreshable braille display to convert text into braille.
Browser: A system entity that is used by an end user to access a Web site. A browser provides a run-time environment for distributed application components on the client's device.
C
Cache: A storage area used by a server or proxy to store data resources that have been retrieved or created in response to a request. When a new request for a "cached" data resource is received, the server or proxy can respond with the cached version instead of retrieving or creating a new copy.
Cacheable: A data resource is said to be "cacheable" if the data resource contains a property that allows a sever to determine whether the cached resource matches a request for a similar resource.
Captions: "Captions" are essential text equivalents for movie audio. Captions consist of a text transcript of the auditory track of the movie (or other video presentation) that is synchronized with the video and auditory tracks. Captions are generally rendered graphically and benefit people who can see but are deaf, hard-of-hearing, or cannot hear the audio.
Captions are text transcripts that are synchronized with other audio tracks or visual tracks. Captions convey information about spoken words and non-spoken sounds such as sound effects. They benefit people who are deaf or hard-of-hearing, and anyone who cannot hear the audio (e.g., someone in a noisy environment). Captions are generally rendered graphically superimposed ("on top of") the synchronized visual track.
Capability: An attribute of a sender or receiver (often the receiver) which indicates an ability to generate or process a particular type of message content.
Cascading Style Sheet (CSS): Style sheets describe how documents are presented on screens, in print, and even in spoken voice. Style sheets allow the user to change the appearance of hundreds of Web pages by changing just one file. A style sheet is made up of rules that tell a browser how to present a document. Numerous properties may be defined for an element; each property is given a value.
Character: Strings consist of a sequence of zero or more characters, where a character is defined as in the XML Recommendation [XML].
Characters: A character is a printable symbol having phonetic or pictographic meaning and usually forming part of a word of text, depicting a numeral, or expressing grammatical punctuation. A character is generally one of a limited number of symbols, including the letters of a particular language's alphabet, the numerals in the decimal number system, and certain special symbols such as the ampersand and "atsign" @. Several standards of computer encoding have been developed for characters. The most commonly used in personal computers is ASCII. IBM mainframe systems use extended binary-coded decimal interchange code. A new standard, Unicode, is supported by the Windows NT system. A distinction is sometimes made between a character and a glyph. In this distinction, a character can be distinguished from other characters in terms of meaning and sound and a glyph is the graphic image used to portray the character. In different implementations, a character can have more than one possible glyph, and a glyph can represent more than one possible character.
Character Codes: A show string is the encoded re of a sequence of non-negative integers. Each of those integers is a Character Code. The interpretation of a show string depends on the associated font: some fonts imply a one-byte re whie others imply a more complicated re. A mapping from a set of integers to a set of characters. This mapping is generally 1:1 (i.e., bijective), for example, the code position 65 in ASCII maps only to "A", and it's the only position that maps to "A". There are several standard coded character sets, the most widely used is ASCII, generally in its Latin-1 dialect (the ASCII coded character set, encoded directly as single-byte values), or UTF-8 (the Unicode coded character set, encoded with an 8-bit transformation method), with Unicode becoming slowly more common; while EBCDIC and Baudot are extinct except in legacy systems. A coded character set may include letters, digits, punctuation, control codes, various mathematical and typographic symbols, and other characters. Each character in the set is represented by a unique character code (or "code position").
Character Encoding: A "character encoding" is a mapping from a character set definition to the actual code units used to represent the data. Please refer to the Unicode specification [UNICODE] for more information about character encodings. Refer to "Character Model for the World Wide Web" [CHARMOD] for additional information about characters and character encodings.
CMS: CMS or Content Management System is a software system used for content management. This includes computer files, image media, audio files, electronic documents and web content. The idea behind a CMS is to make these files available inter-office, as well as over the web.
Cognitive and Neurological Disabilities: Attention Deficit Disorder (ADD), Dyslexia, Dyscalculia, Attention Deficit Hyperactive Disorder (ADHD), Impairments of Intelligence, or Learning Disabilities, Memory Impairments, Mental Health Disabilities, Seizure Disorders
Colour Blindness: Colour blindness is a lack of sensitivity to certain colours. Common forms of colour blindness include difficulty distinguishing between red and green, or between yellow and blue. Sometimes colour blindness results in the inability to perceive any colour.
Component: A component is a software object, meant to interact with other components, encapsulating certain functionality or a set of functionalities. A component has a clearly defined interface and conforms to a prescribed behavior common to all components within an architecture.; A component is an abstract unit of software instructions and internal state that provides a transformation of data via its interface.
Conditional-content: Conditional content is content that, by format specification, should be made available to users through the user interface, generally under certain conditions (e.g., user preferences or operating environment limitations).
Connection: a transport layer virtual circuit established between two programs for the purpose of communication.
Content: Content refers to the document object as a whole or in parts. Phrases such as "content type", "text content", and "language of content" refer to this usage. When used in this sense, the term content encompasses equivalent alternatives. Refer also to the definition of rendered content. and other accessibility information.; Content refers to the content of an HTML or XML element, in the sense employed by the XML 1.0 specification ( XML, section 3.1): "The text between the start-tag and end-tag is called the element's content." Context should indicate that the term content is being used in this sense.
Context: A context specifies an access pattern (or path): a set of interfaces which give you a way to interact with a model.
Contrast: A difference in visual attributes (e.g., hue, lightness, saturation) of an object's foreground and background.
Cookie: Data sent by a Web server to a Web client, to be stored locally by the client and sent back to the server on subsequent requests.
Country Code: An identifier that is defined for a nation by ISO. For each nation, ISO Standard 3166 defines a unique two- character alphabetic code, a unique three-character alphabetic code, and a three-digit code. Among many uses of these codes, the two-character codes are used as top-level domain names.
D
Data: Information in a specific physical representation, usually a sequence of symbols that have meaning; especially a representation of information that can be processed or produced by a computer.
Deprecated: A deprecated element or attribute is one that has been outdated by newer constructs. Deprecated elements may become obsolete in future versions of HTML. Authors should avoid using deprecated elements and attributes. User agents should continue to support for reasons of backward compatibility.
Device-dependent: Used to describe event handlers that require a specific kind of input device. For example, onDblClick requires a mouse; there is no keyboard equivalent for double clicking. Input devices may include pointing devices (such as the mouse), keyboards, braille devices, head wands, microphones, and others. Output devices may include monitors, speech synthesizers, and braille devices. Scripting should be device-independent or provide multiple input and output options for different devices.
Device Independent: Users must be able to interact with a (and the document it renders) using the supported input and output devices of their choice and according to their needs. Input devices may include pointing devices, keyboards, braille devices, head wands, microphones, and others. Output devices may include monitors, speech synthesizers, and braille devices.
Device-independence: "Device-independence" refers to the desirable property that operation of a user agent feature is not bound to only one input or output device.
Description Link (D-link): A "description link", or D-Link, is an author-supplied link to additional information about a piece of content that might otherwise be difficult to access (image, applet, video, etc.).
Device: An apparatus through which a user can perceive and interact with the web.
Disability: The term disability refers to a physical or mental handicap either congenital or caused by injury, disease, etc. that prevents a person from doing something. There are many disabilities that affect web use some of them are: visual (blindness, low vision,colour blindness), hearing (deafness, hard of hearing), physical and motor disabilities, speach disabilities, cognitive and neurological disabilities (dyslexia, dycalculia, attention deficit disorder, intellectual disabilities, memory imparements, mental health disabilities, seizure disorders), multiple disabilities and aging-related conditions.
Document: A "document" is a series of elements that are defined by a markup language (e.g., HTML 4 or an XML application).
Document Content, Structure, and Presentation: The content of a document refers to what it says to the user through natural language, images, sounds, movies, animations, etc. The structure of a document is how it is organized logically (e.g., by chapter, with an introduction and table of contents, etc.). An element (e.g., P, STRONG, BLOCKQUOTE in HTML) that specifies document structure is called a structural element. The presentation of a document is how the document is rendered (e.g., as print, as a two-dimensional graphical , as an text-only , as synthesized speech, as braille, etc.) An element that specifies document (e.g., B, FONT, CENTER) is called a presentation element. Consider a document header, for example:. The content of the header is what the header says (e.g., "Sailboats"). In HTML, the header is a structural element marked up with.
E
End User: A natural person who makes use of resources for application purposes.
Entity: Entities allow you to use reserved markup characters, for example, the greater than sign (>), in your document without having the parser read them as markup.
Equivalent: Content is "equivalent" to other content when both fulfill essentially the same function or purpose upon to the user. In the context of this WC document, the equivalent must fulfill essentially the same function for the person with a disability (at least insofar as is feasible, given the nature of the disability and the state of technology), as the primary content does for the person without any disability.
Equivalent (for Content): An equivalency relationship between two pieces of content means that one piece -- the "equivalent" -- is able to serve essentially the same function for a person with a disability (at least insofar as is feasible, given the nature of the disability and the state of technology) as the other piece -- the "equivalency target" -- does for a person without any disability.
Equivalent Alternatives for Content: Since content in some forms is not always accessible to users with disabilities, authors must provide equivalent alternatives for inaccessible content. In the context of this [UA] document, the equivalent must fulfill essentially the same function for the person with a disability (at least insofar as is feasible, given the nature of the disability and the state of technology), as the "primary" content does for the person without any disability.
F
Feature: Functional property of a device or entity.
Font: A font represents an organized collection of glyphs in which the various glyph representations will share a common look or styling such that, when a string of characters is rendered together, the result is highly legible, conveys a particular artistic style and provides consistent inter-character alignment and spacing.
G
Generation Tool: A "generation tool" is a program or script that produces automatic markup "on the fly" by following a template or set of rules. The generation may be performed on either the server or client side.
Global Configuration: A global configuration is one that applies across elements of the same Web resource, as well as across Web resources. A global configuration may be implemented by more than one setting (e.g., per component of the user agent). For instance, when a user agent consists of a browser that renders HTML and a plug-in that renders SVG, to satisfy the global configuration requirements of this document, the browser may provide one setting and the plug-in another.
Glyph: A glyph represents a unit of rendered content within a font. Often, there is a one-to-one correspondence between characters to be drawn and corresponding glyphs (e.g., often, the character "A" is rendered using a single glyph), but other times multiple glyphs are used to render a single character (e.g., use of accents) or a single glyph can be used to render multiple characters (e.g., ligatures). Typically, a glyph is defined by one or more shapes such as a path, possibly with additional information such as rendering hints that help a font engine to produce legible text in small sizes.; An image used in the visual re of characters; roughly speaking, how a character looks. A font is a set of glyphs. In the simple case, for a given font (typeface and size), each character corresponds to a single glyph but this is not always the case, especially in a language with a large alphabet where one character may correspond to several glyphs or several characters to one glyph (a character encoding). A glyph can be an alphabetic or numeric font or some other symbol that pictures an encoded character. The following quote is from a document written as background for the Unicode character set standard. An ideal characterization of characters and glyphs and their relationship may be stated as follows: A character conveys distinctions in meaning or sounds. A character has no intrinsic appearance. A glyph conveys distinctions in form. A glyph has no intrinsic meaning. One or more characters may be depicted by one or more glyph res (instances of an abstract glyph) in a possibly context dependent fashion. Glyph is from a Greek word for "carving".
Graphics: Two- or three-dimensional images, typically drawings or photographs.
H
Hearing Disabilities: Deafness, Hard of Hearing
Highlight: To "highlight" means to emphasize through the user interface. User agents highlight which content is selected or focused. Graphical highlight mechanisms include dotted boxes, underlining, and reverse video. Synthesized speech highlight mechanisms include alterations of voice pitch and volume ("speech prosody").
Hint: A suggestion or preference for a particular option. While this option is strongly recommended, its use is not required.
Hyperlink: A pointer within a hypertext document which points (links) to another document, which may or may not also be a hypertext document. See also: hypertext.
Hypertext: A document, written in HTML, which contains hyperlinks to other documents, which may or may not also be hypertext documents. Hypertext documents are usually retrieved using the World Wide Web WWW.
I
Image: An image is a primarily symbolic visual representation other than text.
Impairment: An impairment refers to an abnormality of body structure, appearance, organ and system functioning. Impairments are problems in body function or structure such as a significant deviation or loss.
Impairments of Intelligence: Individuals with impairments of intelligence (sometimes called "learning disabilities" in Europe) may learn more slowly, or have difficulty understanding complex concepts.
Important: Information in a document is important if understanding that information is crucial to understanding the document.
Inform: To "inform" is to make the author aware of an event or situation through alert, prompt, sound, flash, or other means.
Information Appliances: Information appliances are targeted for particular uses. They support the features they need for the functions they are designed to fulfill. The following are examples of different information appliances: Mobile phones, Televisions, PDAs, Vending machines, Pagers, Car navigation systems, Mobile game machines, Digital book readers, Smart watches
Interaction: The act of doing an operation.
Interactive Elements, Non-interactive Elements: An interactive element is piece of content that, by specification, may have associated behaviors to be executed or carried out as a result of user or programmatic interaction. For instance, the interactive elements of HTML 4 [HTML4] include: links, image maps, form elements, elements with a value for the longdesc attribute, and elements with event handlers explicitly associated with them (e.g., through the various "on" attributes). The role of an element as an interactive element is subject to applicability. A non-interactive element is an element that, by format specification, does not have associated behaviors. The expectation of this document is that interactive elements become enabled elements in some sessions, and non-interactive elements never become enabled elements.
Interface: A logical grouping of operations. An Interface represents an abstract Service type, independent of transmission protocol and data format.
Interoperability: The ability of software and hardware on multiple machines from multiple vendors to communicate meaningfully.
J
K
Keyboard: A hardware device (or logical equivalent) consisting of a number of mechanical buttons (keys) that the user presses to input characters to a computer. Note that a logical keyboard may provide a representation of keys (e.g., on-screen keyboard) or it may not (e.g., voice recognition).
Keyboard Equivalents: Keys or key combinations that provide access to keyboard functions that are usually activated by a pointing device, voice input, or other input or control mechanisms/devices.
L
Linearized Table: A table rendering process where the contents of the cells become a series of paragraphs (e.g., down the page) one after another. The paragraphs will occur in the same order as the cells are defined in the document source. Cells should make sense when read in order and should include structural elements (that create paragraphs, headers, lists, etc.) so the page makes sense after linearization.
Line-break Hyphen: Hyphens that you add explicitly by entering the dash character are called line-break or hard hyphens. A hyphen that is always set; for example, the hyphen in "cost-effective." A soft hyphen, by contrast, will only be set when a word that is not normally hyphenated falls at the end of a line, and must be broken for proper type spacing. Word processors use two basic techniques to perform hyphenation. The first employs an internal dictionary of words that indicates where hyphens may be inserted. The second uses a set of logical formulas to make hyphenation decisions. The dictionary method is more accurate but is usually slower. The most sophisticated programs use a combination of both methods. Most word processors allow you to override their own hyphenation rules and define yourself where a word should be divided.
Live: Real-time, Real-time process, Real-time event
M
Markup Language: Authors encode information using a "markup language" such as HTML HTML 4.01, SVG SVG, or MathML MATHML.
Memory Impairments: Individuals with memory impairments may have problems with short-term memory, missing long-term memory, or some loss of language.
Mental Health Disabilities: Individuals with mental or emotional disabilities may have difficulty focusing on information on a Web site, or difficulty with blurred vision or hand tremors due to side effects from medications.
Metadata: Data about data on the Web, including but not limited to authorship, classification, endorsement, policy, distribution terms, IPR, and so on. A significant use for the Semantic Web.; Data that describes data. Data dictionaries and repositories are examples of metadata. The term may also refer to any file or database that holds information about another database's structure, attributes, processing or changes.
Method: A method is an operation or function that is associated with an object and is allowed to manipulate the object's data.
Mnemonic: The portion of an option name or control label used for keyboard selection. Also called mnemonic, implicit designator, or menu mnemonic.
Mnemonic Code: A code that conveys information that is meaningful to the user and has some association with the words it represents. Mnemonic codes frequently consist of alphanumeric characters, making them easier to learn and recall. Many mnemonic codes are abbreviations.
Modifier Key: A keyboard key that changes the action or effect of another key or of the pointing device.
Multimedia Presentation: A multimedia presentation is a presentation that is not a visual-only, audio-only, or tactile-only. In a "classic" multimedia (e.g., a movie that has sound track or an animation with accompanying audio, including slide-shows), at least one visual track is closely synchronized with at least one audio track.
N
Namespace: A qualifier added to an XML tag to ensure uniqueness among XML elements.
Native Support: A user agent supports a feature natively if it does not require another piece of software (e.g., plug-in or external program) for support. Operating system features adopted by the user agent to meet the requirements of this [UA] document are considered part of native support. User agents may, but are not required to, provide access to adopted operating system features through the user agent's user interface or programmatic means.
Natural Language: Natural language is spoken, written, or signed human language such as French, Japanese, and American Sign Language. On the Web, the natural language of content may be specified by markup or HTTP headers. Some examples include the lang attribute in HTML 4, the xml:lang attribute in XML 1.0, the hreflang attribute for links in HTML 4, the HTTP Content-Language header and the Accept-Language request header.
Negotiation Metadata: Information which is exchanged between the sender and the receiver of a message by content negotiation in order to determine the variant which should be transferred.
Non-text Content: Non-text content includes images, text in raster images, image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video.
Non-variant Content: When the form/format of the content being sent does not depend on receiver's capabilities and/or preferences.
Normative: What is identified as "normative" is required for conformance (noting that one may conform in a variety of well-defined ways to this document). What is identified as "informative" (sometimes, "non-normative") is never required for conformance.
O
Objects: An object is an identifiable, encapsulated entity that provides one or more services requested by a client. Objects can refer to the objects in OOP (object-oriented programming) or the objects in OLE (Object Linking and Embedding). In object-oriented programming, objects are the things you think about first in designing a program and they are also the units of code that are eventually derived from the process. In between, each object is made into a generic class of object and even more generic classes are defined so that objects can share models and reuse the class definitions in their code. Each object is an instance of a particular class or subclass with the class's own method or procedures and data variable. An object is what actually runs in the computer. An object can be a spell checker or a piece of a graphics program used to draw squares or circles. Do you remember the crazy story people used to try to tell about a word processer where you could pick all of your favorite pieces (favorite spell checker, grammar checker, text editor, font manager, etc.) and piece them together to form the ultimate customizable word processer? Well, those pieces are objects. In OLE, an object is a piece of a document, a graphic, or some multimedia. In general multimedia terms, an object is a stored data element, such as a video clip, an audio file, or a graphic re of an object.
Obsolete Element: An obsolete element or attribute is one for which there is no guarantee of support by a user agent. Obsolete elements are no longer defined in the specification, but are listed for historical purposes in the changes section of the reference manual.
Operating environment: The term "operating environment" refers to the environment that governs the user agent's operation, whether it is an operating system or a programming language environment such as Java.
Override: The term "override" means that one configuration or behavior preference prevails over another. Generally, the requirements of this document involve user preferences prevailing over author preferences and user agent default settings and behaviors. Preferences may be multi-valued in general (e.g., the user prefers blue over red or yellow), and include the special case of two values (e.g., turn on or off blinking text content ).
P
Parser, Parsing: A parser extracts information from an XML document and parses it back to the application (for example, a browser) for processing or display. Parsing is the act whereby a document is scanned, and the information contained within the document is filtered into the context of the elements in which the information is structured.
Personal Digital Assistant (PDA): A PDA is a small, portable computing device. Most PDAs are used to track personal data such as calendars, contacts, and electronic mail. A PDA is generally a handheld device with a small screen that allows input from various sources.
Personally Identifiable Data: Any information relating to an identified or identifiable individual.
Photosensitive Epilepsy, Photoepilepsy: Some people with epilepsy can be triggered into seizures by flashing or flickering lights, rapidly changing images or visual patterns. This is called photosensitive epilepsy. When given an EEG test, the majority of people with photosensitive epilepsy will show epileptic discharges in the brain when exposed to flashing lights. Epilepsy is best described as a tendency to recurrent convulsions. Photosensitivity is sensitivity to flickering or intermittent light stimulation but includes sensitivity to visual patterns. Photosensitive epilepsy therefore can be defined as recurrent convulsions precipitated by visual stimuli, particularly flickering light (Harding & Jeavons, 1994). Photosensitive epilepsy is largely genetically determined, although its inheritance is complex. It most commonly affects children, and usually appears between the ages of 8 and 20 years. The incidence is highest around ages 12 and 13, suggesting a link with early puberty, and girls are affected more often than boys. One quarter of patients lose their photosensitivity around 25 years of age. The rest remain photosensitive for life.
PHP: PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
Physical Disabilities: Motor Disabilities, Speech Disabilities
Placeholder: A placeholder is content generated by the user agent to replace author-supplied content. A placeholder may be generated as the result of a user preference (e.g., to not render images) or as repair content (e.g., when an image cannot be found). Placeholders can be any type of content, including text, images, and audio cues.
Plaintext: Data that is input to and transformed by an encryption process, or that is output by a decryption process.
Plug-in: A plug-in is a program that runs as part of the user agent and that is not part of content. Users generally choose to include or exclude plug-ins from their user agent.
Pointer: A user interface object represented by a graphical symbol that moves on the screen to reflect the user's manipulation of a pointing device and/or the current state of the dialog or system. Users interact with other objects on the screen by moving the pointer to an object's location and manipulating that object. Examples of pointers include mouse devices, tablets, fingers, and 3 D wands. Pointers may be represented with an auditory representation of a location on the screen. Although the pointer is sometimes called a type of cursor, this document uses the word cursor only for the indication of keyboard input focus or location. Also called On-Screen Pointer.
Policy: A collection of one or more privacy statements together with information asserting the identity, URI, assurances, and dispute resolution procedures of the service covered by the policy.
Practice: The set of disclosures regarding data usage, including purpose, recipients, and other disclosures.
Preference: A rule, or set of rules, that determines what action(s) a user agent will take. A preference might be expressed as a formally defined computable statement.
Presentation: the term presentation refers to a collection of information, consisting of one or more web resources, intended to be rendered simultaneously, and identified by a single URI. In general, a has an inherent time component (i.e., it's not just a static "Web page" (refer to the definition of "Web page" in "Web Characterization Terminology and Definitions Sheet" WEBCHAR).
Presentation Attribute: An XML attribute on an SVG element which specifies a value for a given property for that element.
Presentation Markup: "Presentation markup" is markup language that encodes information about the desired or layout of the content. For example, Cascading Style Sheets (CSS 1, CSS 2) can be used to control fonts, colours, aural rendering, and graphical positioning. Presentation markup should not be used in place of structural markup to convey structure. For example, authors should mark up lists in HTML with proper list markup and style them with CSS (e.g., to control spacing, bullets, numbering, etc.). Authors should not use other CSS or HTML incorrectly to lay out content graphically so that it resembles a list.; Presentation markup is markup that achieves a stylistic (rather than structuring) effect such as the B or I elements in HTML. Note: that the STRONG and EM elements are not considered markup since they convey information that is independent of a particular font style.
Privacy: Preventing the unintended or unauthorized disclosure of information about a person. Such information may be contained within a message, but may also be inferred from patterns of communication; e.g. when communications happen, the types of resource accessed, the parties with whom communication occurs, etc.
Profile: A profile is a named and persistent representation of user preferences that may be used to configure a user agent. Preferences include input configurations, style preferences, and natural language preferences. In operating environments with distinct user accounts, profiles enable users to reconfigure software quickly when they log on. Users may share their profiles with one another. Platform-independent profiles are useful for those who use the same user agent on different platforms.
Prompt: A "prompt" is a request for author input, either information or a decision. A prompt requires author response. For example, a text equivalents entry field prominently displayed in an image insertion dialog would constitute a prompt. Prompts can be used to encourage authors to provide information needed to make content accessible (such as alternative text equivalents).; "to prompt" means to require input from the user. The user agent should allow users to configure how they wish to be prompted. For instance, for a user agent functionality X, configurations might include: "always prompt me before doing X," "never prompt me before doing X," "never do X but tell me when you could have," and "never do X and never tell me that you could have."
Property: A "property" is a piece of information about an element, for example structural information (e.g., it is item number 7 in a list, or plain text) or information (e.g., that it is marked as bold, its font size is 14). In XML and HTML, properties of an element include the type of the element (e.g., IMG or DL), the values of its attributes, and information associated by means of a style sheet. In a database, properties of a particular element may include values of the entry, and acceptable data types for that entry.; A parameter that helps specify how a document should be rendered. A complete list of SVG's properties can be found in Property Index. Properties are assigned to elements in the SVG language either by presentation attributes on elements in the SVG language or by using a styling language such as CSS, CSS 2.
Properties, Values, and Defaults: A user agent renders a document by applying formatting algorithms and style information to the document's elements. Formatting depends on a number of factors, including where the document is rendered: on screen, on paper, through loudspeakers, on a Braille display, on a mobile device. Style information (e.g., fonts, colours, and synthesized speech prosody) may come from the elements themselves (e.g., certain font and phrase elements in HTML), from style sheets, or from user agent settings. The value given to a property by a user agent when it is installed is called the property's default value UA.
Protocol: A set of rules (i.e., formats and procedures) to implement and control some type of association (e.g., communication) between systems. (E.g., Internet Protocol) In particular, a series of ordered steps involving computing and communication that are performed by two or more system entities to achieve a joint objective.
Protocols: A formal description of message formats and the rules two computers must follow to exchange those messages. Protocols can describe low-level details of machine-to-machine interfaces (e.g., the order in which bits and bytes are sent across a wire) or high-level exchanges between allocation programs (e.g., the way in which two programs transfer a file across the Internet).
Publishing Tool: A "publishing tool" is software that allows content to be uploaded in an integrated fashion. Sometimes these tools makes changes such as local hyper-reference modifications. Although these tools sometimes stand alone, they may also be integrated into site management tools.
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Real-time, Real-time process, Real-time event: This term is often written as "realtime" or "real-time". The expression indicates that a process is happening "live", i.e. at the same time as something else. For example, with some audio CoDecs, it is possible to "compress in real time", which in this case can indicate that the digital audio data compression is performed by the computer at the same time as the digitisation and data storing is talking place. To be a true real time process, it must be possible to do the work as fast as, or preferable faster, than the rate at which input data is coming in. If the real time process can not keep up with the tempo of "real life", it is no longer a real-time process.
Recognize: A user agent is said to recognize markup, content types, or rendering effects when it can identify the information. Recognition may occur through built-in mechanisms, Document Type Definitions (DTDs) style sheets, HTTP headers, and other means. User agents may not understand everything the author has encoded in content, such as the semantics of XML elements unknown to the user agent, whether the link text and link title accurately describe the linked resource, whether a sentence (that has not been specially marked up) is a text equivalent for an image, or whether a script is calculating a factorial. Another example of failure of recognition is that HTML 3.2 s may not recognize the new elements or attributes of HTML 4.01 HTML 4.01. While a user agent may recognize blinking content specified by elements or attributes, it may not recognize blinking in an applet. The Techniques document UAAG10-TECHS lists some markup known to affect accessibility that should be recognized by user agents.; Authors encode information in markup languages, style sheet languages, scripting languages, protocols, etc. When the information is encoded in a manner that allows the user agent to process it with certainty, the user agent can "recognize" the information. For instance, HTML allows authors to specify a heading with the H1 element, so a user agent that implements HTML can recognize that content as a heading. If the author creates headings using a visual effect alone (e.g., by increasing the font size), then the author has encoded the heading in a manner that does not allow the user agent to recognize it as a heading.
Registry: A system entity that provides Service and Service Provider information.
Rendered, Rendering: Rendering is the act whereby the information in a document is presented. This presentation is done in the form most appropriate to the environment (e.g. aurally, visually, in print).
Rendered Content, Rendered Text: Rendered content is the part of content capable of being perceived by a user through a given viewport (whether visual, auditory, or tactile). Some rendered content may lie "outside" of a viewport at some times (e.g., when the user can only view a portion of a large document through a small graphical viewport, when audio content has already been played, etc.). By changing the viewport's position, the user can view the remaining rendered content.; The rendered content is that part of content rendered in a given viewport (whether graphical, auditory, or tactile). An element's rendered content is that which a user agent renders for the element. This may be what appears between the element's start and end tags, the value of an attribute (c.f. the "alt", "title", and "longdesc" attributes in HTML), or external data (e.g., the IMG element in HTML). content may be rendered to a graphical display, to an auditory display (to a speaker as speech and non-speech sounds) or to a tactile display (Braille and haptic displays).; The "rendered content" of an element is that which the element actually causes to be rendered by the user agent. This may differ from the element's structural content . For example, some elements cause external data to be rendered , and in some cases, browsers may render the value of an attribute (e.g., "alt", "title") in place of the element's content.; The content of an element after the rendering that applies to it according to the relevant style sheets has been applied. The rendered content of a replaced element comes from outside the source document. Rendered content may also be alternate text for an element (e.g., the value of the HTML "alt" attribute), and may include items inserted implicitly or explicitly by the style sheet, such as bullets, numbering, etc.
Rendered View: A "rendered view" simulates for the author how a user will interact with the content being edited once published.
Replaced Element: An element for which the CSS formatter knows only the intrinsic dimensions. In HTML, IMG, INPUT, TEXTAREA, SELECT, and OBJECT elements can be examples of replaced elements. For example, the content of the IMG element is often replaced by the image that the "src" attribute designates. CSS does not define how the intrinsic dimensions are found.
Repository: A mechanism for storing user information under the control of the user agent.
ReverseChars: Font characteristics may suggest that right-to-left text be typeset left-to-right. The ReverseChars marked content indicates that the show strings within the marked content are individually reversed in reading order.
Rich Media: Rich media refers to elements on a web page (or in a separate player) which exhibit dynamic motion over time or in response to user interaction. The taxonomy defines classes of objects and relations among them.
some examples: A streaming video newscast, An animated GIF in a banner advertisement, A map with audio descriptions of historic locations which are activated by mouse rollover, A stock ticker on a news web site, A intranet-based training video played in a media player, An animated Flash presentation embedded in a web page, An image slideshow playing on a PDA or handheld device
Router: A computer that is a gateway between two networks at OSI layer 3 and that relays and directs data packets through that internetwork. The most common form of router operates on IP packets. In the context of the Internet protocol suite, a networked computer that forwards Internet Protocol packets that are not addressed to the computer itself.
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Scanning Software: Scanning software is adaptive software used by individuals with some physical or cognitive disabilities that highlights or announces selection choices (e.g., menu items, links, phrases) one at a time. A user selects a desired item by hitting a switch when the desired item is highlighted or announced.
Schema, RDF Schema: An RDF schema denotes resources which constitute the particular unchanging versions of an RDF vocabulary at any point in time. It is used to provide semantic information (such as organization and relationship) about the interpretation of the statements in an RDF data model. It does not include the values associated with the attributes.
Screen Magnifier: A software program that magnifies a portion of the screen, so that it can be more easily viewed. Screen magnifiers are used primarily by individuals with low vision.; Screen magnification is software used primarily by individuals with low vision that magnifies a portion of the screen for easier viewing. At the same time screen magnifiers make presentations larger, they also reduce the area of the document that may be viewed, removing surrounding context . Some screen magnifiers offer two views of the screen: one magnified and one default size for navigation.
Screen Reader: A software program that reads the contents of the screen aloud to a user. Screen readers are used primarily by individuals who are blind. Screen readers can usually only read text that is printed, not painted, to the screen.; Software used by individuals who are blind or who have dyslexia that interprets what is displayed on a screen and directs it either to Speech Synthesis for audio output, or to refreshable braille for tactile output. Some screen readers use the document tree (i.e., the parsed document code) as their input. Older screen readers make use of the rendered version of a document, so that document order or structure may be lost (e.g., when tables are used for layout) and their output may be confusing.; Assistive technology (software, and sometimes additional hardware), in combination with information available via the operating system, that allows users who are blind to navigate the user interface, determine the state of controls, and read text via Braille or hear it via text-to-speech conversion.
Script: the term "script" almost always refers to a scripting (programming) language used to create dynamic Web content. However, in checkpoints referring to the written (natural) language of content, the term "script" is used as in Unicode [UNICODE] to mean "A collection of symbols used to represent textual information in one or more writing systems." Information encoded in (programming) scripts may be difficult for a user agent to recognize. For instance, a user agent is not expected to recognize that, when executed, a script will calculate a factorial. The user agent will be able to recognize some information in a script by virtue of implementing the scripting language or a known program library (e.g., the user agent is expected to recognize when a script will open a viewport or retrieve a resource from the Web).
Security: Describes a set of procedures applied to data communications to ensure that information is transferred exactly as the sender and receiver intend, and in no other way. Security generally breaks down into Integrity, Authentication, Confidentiality and Privacy.
Seizure Disorders: Some individuals with seizure disorders are triggered by visual flickering or audio signals at a certain frequency.
Selection: A "selection" is a set of elements identified for a particular operation. The user selection identifies a set of elements for certain types of user interaction (e.g., cut, copy, and paste operations). The user selection may be established by the user (e.g., by a pointing device or the keyboard) or via an accessibility Application Programmatic Interface (API). A view may have several selections, but only one user selection.
Semantics: Semantics is the study of language meaning. The study of relationships between signs and symbols and what they represent. In this sense, also called semasiology. The meaning of a string in some language, as opposed to syntax which describes how symbols may be combined independent of their meaning.
Sender-initiated Transmission: A message transmission which is invoked by the sender of the message. Sometimes described as "push" messaging. E.g. sending an email.
Serial Access, Sequential Navigation: the expression "serial access" refers to one-dimensional access to rendered content. Some examples of serial access include listening to an audio stream or watching a video (both of which involve one temporal dimension), or reading a series of lines of braille one line at a time (one spatial dimension). Many users with blindness have serial access to content rendered as audio, synthesized speech, or lines of braille.
The expression "sequential navigation" refers to navigation through an ordered set of items (e.g., the enabled elements in a document, a sequence of lines or pages, or a sequence of menu options). Sequential navigation implies that the user cannot skip directly from one member of the set to another, in contrast to direct or structured navigation (see guideline 9 for information about these types of navigation). Users with blindness or some users with a physical disability may navigate content sequentially (e.g., by navigating through links, one by one, in a graphical viewport with or without the aid of an assistive technology). Sequential navigation is important to users who cannot scan rendered content visually for context and also benefits users unfamiliar with content. The increments of sequential navigation may be determined by a number of factors, including element type (e.g., links only), content structure (e.g., navigation from heading to heading), and the current navigation context (e.g., having navigated to a table, allow navigation among the table cells).
Server: An application program that accepts connections in order to service requests by sending back responses. Any given program may be capable of being both a client and a server; our use of these terms refers only to the role being performed by the program for a particular connection, rather than to the program's capabilities in general. Likewise, any server may act as an origin server, proxy, gateway, or tunnel, switching behavior based on the nature of each request.
Server-side Scripting: Web programming that is carried out on the Web server, as opposed to the client's computer. Pages programmed with server-side scripting do not require any special capabilities on the part of the user's computer or browser.
Service: A program that issues policies and (possibly) data requests. By this definition, a service may be a server (site), a local application, a piece of locally active code, such as an ActiveX control or Java applet, or even another user agent.; A service is a system that provides one or more functions of value to the end-user. Examples include: a photocopying service, a banking service, an authentication service, interlibrary loans, a Z39.50 or Web server.
Session: A lasting interaction between system entities, often involving a user, typified by the maintenance of some state of the interaction for the duration of the interaction. A lasting interaction between system entities, often involving a user, typified by the maintenance of some state of the interaction for the duration of the interaction.
Simpler-language Alternative: Is comparable information on the same subject which is written at a more introductory or elementary level.
Site Management Tool: A "site management tool" provides an overview of an entire Web site indicating hierarchical structure. It will facilitate management through functions that may include automatic index creation, automatic link updating, and broken link checking.
Soft Hyphen: A character that is used to mark conditional hyphenation points. Unicode and ISO_Latin-1 code-point 0xAD.
Speech Synthesis: The process of automatic generation of speech output from data input which may include plain text, formatted text or binary objects.
State: A set of attributes representing the properties of a component at some point in time.
Support, Implement, Conform: The terms "support," "implement," "conform" all refer to what a developer has designed a user agent to do, but they represent different degrees of specificity. A user agent "supports" general classes of objects, such as "images" or "Japanese." A user agent "implements" a specification (e.g., the PNG and SVG image format specifications or a particular scripting language), or an API (e.g., the DOM API) when it has been programmed to follow all or part of a specification. A user agent "conforms to" a specification when it implements the specification and satisfies its conformance criteria.
Synchronize: "To synchronize" refers to the act of time-coordinating two or more presentation components (e.g., a visual track with captions, or several tracks in a multimedia presentation). For Web content developers, the requirement to synchronize means to provide the data that will permit sensible time-coordinated rendering by a user agent. For example, Web content developers can ensure that the segments of caption text are neither too long nor too short, and that they map to segments of the visual track that are appropriate in length. For user agent developers, the requirement to synchronize means to present the content in a sensible time-coordinated fashion under a wide range of circumstances including technology constraints (e.g., small text-only displays), user limitations (slow reading speeds, large font sizes, high need for review or repeat functions), and content that is sub-optimal in terms of accessibility.
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Tab Order: An assistive technology strategy. For people who cannot use a mouse, one strategy for rapidly scanning through links, headers, list items, or other structural items on a Web page is to use the tab key to go through the items in sequence. People who are using screen readers -- whether because they are blind or dyslexic -- may tab through items on a page, as well as people using voice recognition.
Tabular Information: When tables are used to represent logical relationships among data -- text, numbers, images, etc., that information is called "tabular information" and the tables are called "data tables". The relationships expressed by a table may be rendered visually (usually on a two-dimensional grid), aurally (often preceding cells with header information), or in other formats.
Tactile Object: A tactile object is output from a tactile viewport Tactile objects include text (rendered as Braille) and graphics (rendered as raised-line drawings).
Tactile-only Presentation: A tactile-only presentation is a presentation consisting exclusively of one or more tactile tracks presented concurrently or in series.
Tactile Track: A tactile track is a tactile object that is intended as a whole or partial presentation . This does not necessarily correspond to a single physical or logical track on the storage or delivery media.
Tagged PDF: Is a version of PDF that provides structure and orders information to allow PDF documents to be read by screen-readers and to be reflowed to fit different display screen sizes. To accomplish this, Tagged PDF marks, or tags, the various elements that make up a page.
Telecommunication: The transmission, between or among points specified by the user, of information of the user's choosing, without change in the form or content of the information as sent and received.; The transmission of information over a communications line.Telecommunications can include use of a modem, fax, telephone line, etc. to send voice, data, text, images, or video over long distances.
Text: A text is a resource whose content is primarily words for reading.; The term "text" used by itself refers to a sequence of characters from a markup language's document character set. Refer to the "Character Model for the World Wide Web" CHARMOD for more information about text and characters.
Note: This document makes use of other terms that include the word "text" that have highly specialized meanings: collated text transcript, non-text content, text content, non-text element, text element, text equivalent, and text transcript.
Text Content, non-text content, text element, non-text element, text equivalent, non-text equivalent: a "text element" adds text characters to either content or the user interface. Text elements are presumed to produce text that can be understood when rendered visually, as synthesized speech, or as Braille.
Such text elements benefit at least these three groups of users: visually-displayed text benefits users who are deaf and adept in reading visually-displayed text; synthesized speech benefits users who are blind and adept in use of synthesized speech; braille benefits users who are blind, and possibly deaf-blind, and adept at reading braille.
A text element may consist of both text and non-text data. For instance, a text element may contain markup for style (e.g., font size or colour), structure (e.g., heading levels), and other semantics. The essential function of the text element should be retained even if style information happens to be lost in rendering. A user agent may have to process a text element in order to have access to the text characters. For instance, a text element may consist of markup, it may be encrypted or compressed, or it may include embedded text in a binary format (e.g., JPEG).; "Text content" is content that is composed of one or more text elements. A "text equivalent" (whether in content or the user interface) is an equivalent composed of one or more text elements. Authors generally provide text equivalents for content by using the conditional content mechanisms of a specification.; A "non-text element" is an element (in content or the user interface) that does not have the qualities of a text element. "Non-text content" is composed of one or more non-text elements. A "non-text equivalent" (whether in content or the user interface) is an equivalent composed of one or more non-text elements.
Text Browsers: An assistive technology device. Text browsers such as Lynx are an alternative to graphical user interface browsers. They can be used with screen readers for people who are blind. They are also used by many people who have low bandwidth connections and do not want to wait for images to download.
Text Content Element: One of SVG's elements that can define a text string that is to be rendered onto the canvas. SVG's text content elements are the following: 'text', 'tspan', 'tref' and 'textPath'.
Text Cursor: The visual indication of the current insertion point for text entry-that is, the character position where text will be inserted into a text entry field or other text-based area (e.g., the document window in a word processor). Contrast with pointer and focus cursor.
Text Decoration: A"text decoration" is any stylistic effect that the user agent may apply to visually rendered text that does not affect the layout of the document (i.e., does not require reformatting when applied or removed). Text decoration mechanisms include underline, overline, and strike-through.
Text Equivalent: Text is "equivalent" to other content when both fulfill essentially the same function or purpose upon presentation to the user. Equivalent alternatives play an important role in accessible authoring practices since certain types of content may not be accessible to all users (e.g., video, images, audio, etc.). Authors are encouraged to provide text equivalents for non-text content since text may be rendered as synthesized speech for individuals who have visual or learning disabilities, as braille for individuals who are blind, or as graphical text for individuals who are deaf or do not have a disability.
Text-To-Speech: A text transcript is a text equivalent of audio information (e.g., an audio-only presentation or the audio tracks of a movie or other animation). It provides text for both spoken words and non-spoken sounds such as sound effects. Text transcripts make audio information accessible to people who have hearing disabilities and to people who cannot play the audio. Text transcripts are usually created by hand but may be generated on the fly (e.g., by voice-to-text converters). Refer also to the definitions of captions and collated text transcripts.
Text Transcript: A text transcript is a text equivalent of audio information (e.g., an audio-only presentation or the audio tracks of a movie or other animation). It provides text for both spoken words and non-spoken sounds such as sound effects. Text transcripts make audio information accessible to people who have hearing disabilities and to people who cannot play the audio. Text transcripts are usually created by hand but may be generated on the fly (e.g., by voice-to-text converters). Refer also to the definitions of captions and collated text transcripts.
Time-Out: Period of time after which some condition becomes true if some event has not occurred. For example, a session that is terminated because its state has been inactive for a specified period of time is said to "time out".
Trailing Space Character: A white space character inserted into the text for a page after the last word on a line. A trailing space character is not needed to produce the correct page image, but is important for determining word breaks in the text of the page.
Transcript: A "transcript" is a text representation of sounds in an audio clip or an auditory track of a multimedia presentation. A "collated text transcript" for a video combines (collates) caption text with text descriptions of video information (descriptions of the actions, body language, graphics, and scene changes of the visual track). Collated text transcripts are essential for individuals who are deaf-blind and rely on braille for access to movies and other content .
Transform Gracefully: Graceful transformation is a property of a system that can still function relatively error free when the system is damaged or when the input stimuli are incomplete. In such systems, removing a symbol token only results in the loss of the information stored in that token, with no abrupt performance decline of the overall process.
For instance, suppose I need to check the online yellow line train schedule and I don't have visual access to the Web. If the train Web site uses a yellow wagon animated icon to point me at the schedule, and do not provide a label somewhere saying that this is for the yellow line, thus only relying on my capacity to see the colour, I suddenly cannot understand this site: it does not transform gracefully.
Transform Gracefully, Graceful Degradation: Since HTML is continually changing and different browsers support different elements, graceful degradation is the key to making sure that pages are readable and accessible in all browsers. When a browser encounters tags it doesn't understand or can't display, degradation takes place. Whether this degradation will cause some of your page content to be lost to the browser, or whether the content of your page can still be accessed fully is dependent on whether the degradation is graceful.
The HTML standards were written with graceful degradation in mind - new attributes to older tags are safely ignored so that the rest of the tag can still function normally, and new tags are written with alternative display for browsers that don't support them in mind. There are many elements of HTML that can't be displayed or can be turned off in browsers that were written with the knowledge of these elements- such as images, java, and frames. Using the appropriate methods to provide an alternative message to those who can't see those elements or have turned them off is one way to design for graceful degradation.
If you design pages with graceful degradation in mind, by utilizing the built in elements of the HTML standards, and the advice provided here, you can design pages that should degrade gracefully in all browsers and are accessible.
Transformation: A "transformation" is a process that changes a document or object into another, equivalent, object according to a discrete set of rules. This includes conversion tools, software that allows the author to change the DTD defined for the original document to another DTD, and the ability to change the markup of lists and convert them into tables.
Transformation Filter: Tools that assist Web users (rather than authors) to either modify a page or supplement an assistive technology or browser. Some of these tools integrate into the browser although most of them work by proxy: using a piece of software that sits between the user and the target server to transform a page to make it more accessible.
Transformation Matrix: Transformation matrices define the mathematical mapping from one coordinate system into another using a 3x3 matrix using the equation [x' y' 1] = [x y 1] * matrix. See current transformation matrix (CTM) and Coordinate system transformations.
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Unicode: A character coding scheme that uses 16 bits for each character, designed to extend the capabilities of ASCII, which uses seven bits. Nearly all letters and symbols in all languages can be represented in a standard way with Unicode. The first 128 characters of Unicode are identical to those in standard ASCII. Unicode is an entirely new idea in setting up binary codes for text or script characters. Officially called the Unicode Worldwide Character Standard, it is a system for "the interchange, processing, and display of the written texts of the diverse languages of the modern world." It also supports many classical and historical texts in a number of languages. Currently, the Unicode standard contains 57709 distinct coded characters derived from 24 supported language scripts. These characters cover the principal written languages of the world. Originally Unicode was designed to be universal, unique, and uniform, i.e., the code was to cover all major modern written languages (universal), each character was to have exactly one encoding (unique), and each character was to be represented by a fixed width in bits (uniform). Parallel to the development of Unicode an ISO/IEC standard was being worked on that put a large emphasis on being compatible with existing character codes such as ASCII or ISO Latin 1. To avoid having two competing 16-bit standards, in 1992 the two teams compromised to define a common character code standard, known both as Unicode and BMP. Since the merger the character codes are the same but the two standards are not identical. The ISO/IEC standard covers only coding while Unicode includes additional specifications that help implementation. Unicode is not a glyph encoding. The same character can be displayed as a variety of glyphs, depending not only on the font and style, but also on the adjacent characters. A sequence of characters can be displayed as a single glyph or a character can be displayed as a sequence of glyphs. Which will be the case, is often font dependent.
Unicode Value: Unicode value or code point: The Unicode Consortium defined a set of sixteen-bit code points, 57709 of which are currently assigned and named Unicode Characters. The lowest 65536 code-points in ISO 10646-1 1993 are idential to the Unicode Standard and are sometimes called the Basic Multilingual Plane. See http://www.unicode.org
User: An individual or group of individuals acting as a single entity. The user is further qualified as an entity who uses a device to request content and/or resource from a server.; An individual (or group of individuals acting as a single entity) on whose behalf a service is accessed and for which personal data exists.
User Agent: A "user agent" is software that retrieves and renders Web content. User agents include browsers, plug-ins for a particular media type, and some assistive technologies.; Software to access Web content, including desktop graphical browsers, text browsers, voice browsers, mobile phones, multimedia players, plug-ins, and some software assistive technologies used in conjunction with browsers such as screen readers, screen magnifiers, and voice recognition software.; A program whose purpose is to mediate interactions with services on behalf of the user under the user's preferences. A user may have more than one user agent, and agents need not reside on the user's desktop, but any agent must be controlled by and act on behalf of only the user. The trust relationship between a user and his or her agent may be governed by constraints outside of P3P. For instance, an agent may be trusted as a part of the user's operating system or Web client, or as a part of the terms and conditions of an ISP or privacy proxy.
User Agent Default Styles: User agent default styles are style property values applied in the absence of any author or user styles. Some markup languages specify a default rendering for documents in that markup language. Other specifications may not specify default styles.
User Agent Profile: Capabilities and preference Information pertaining to the capabilities of the device, the operating and network environment, and users personal preferences for receiving content and/or resource.
User Coordinate System, User Space: In general, a coordinate system defines locations and distances on the current canvas. The current user coordinate system is the coordinate system that is currently active and which is used to define how coordinates and lengths are located and computed, respectively, on the current canvas.
User-Configurable Schedule: A "user-configurable schedule" allows the user to determine the type of prompts and alerts that are used, including when they are presented.
User-initiated and User Agent-initiated: User-initiated actions result from user input to the user agent. User Agent-initiated actions result from scripts, operating system conditions, or built-in user agent behavior.; An action initiated by the user is one that results from user operation of the user interface. An action initiated by the user agent is one that results from the execution of a script (e.g., an event handler bound to an event not triggered through the user interface), from operating system conditions, or from built-in behavior.
User interface: the user agent user interface, i.e., the controls (e.g., menus, buttons, prompts, and other components for input and output) and mechanisms (e.g., selection and focus) provided by the user agent ("out of the box") that are not created by content.; the "content user interface," i.e., the enabled elements that are part of content, such as form controls, links, and applets.; The term "user interface control" refers to a component of the user agent user interface or the content user interface, distinguished where necessary.
User Name: Any interactive form field may contain the optional /TU entry in its dictionary. This entry, known as the user name or short description, is used to identify this field when generating an error message or naming the field to a screen reader.
User Identity: The unique identity for a user with a system.
User Styles: User styles are style property values that come from user interface settings, user style sheets, or other user interactions.
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Variant: One of several possible representations of a data resource.
Variant Content: When the form/format of the content being sent depends on receiver's capabilities and/or preferences.
View: Authoring tools may render the same content in a variety of ways; each rendering is called a "view." Some authoring tools will have several different types of view, and some allow views of several documents at once. For instance, one view may show raw markup, a second may show a structured tree, a third may show markup with rendered objects while a final view shows an example of how the document may appear if it were to be rendered by a particular browser. A typical way to distinguish views in a graphic environment is to place each in a separate window.
View, Viewport: The user agent renders content through one or more viewports. Viewports include windows, frames, pieces of paper, loudspeakers, and virtual magnifying glasses. A viewport may contain another viewport (e.g., nested frames). User agent user interface controls such as prompts, menus, and alerts are not viewports.
Graphical and tactile viewports have two spatial dimensions. A viewport may also have temporal dimensions, for instance when audio, speech, animations, and movies are rendered. When the dimensions (spatial or temporal) of rendered content exceed the dimensions of the viewport, the user agent provides mechanisms such as scroll bars and advance and rewind controls so that the user can access the rendered content "outside" the viewport.; When several viewports coexist, only one has the current focus at a given moment. This viewport is highlighted to make it stand out.; User agents may render the same content in a variety of ways; each rendering is called a view. For instance, a user agent may allow users to view an entire document or just a list of the document's headers. These are two different views of the document.
Viewport: Is a rectangular region within the current canvas onto which graphics elements are to be rendered. See the discussion of the SVG viewport in the chapter on Coordinate Systems, Transformations and Units.
Viewport Coordinate System, Viewport Space: In general, a coordinate system defines locations and distances on the current canvas. The viewport coordinate system is the coordinate system that is active at the start of processing of an 'svg' element, before processing the optional viewBox attribute. In the case of an SVG document fragment that is embedded within a parent document which uses CSS to manage its layout, then the viewport coordinate system will have the same orientation and lengths as in CSS, with the origin at the top-left on the viewport. See The initial viewport and Establishing a new viewport.
Viewport Units: A coordinate value or length expressed in viewport units represents a coordinate value or length in the viewport coordinate system. Thus, 10 viewport units represents a length of 10 units in the viewport coordinate system.
Visual Disabilities: Blindness, Low Vision, Colour Blindness
Visual Object: A visual object is output from a visual viewport. Visual objects include graphics, text, and visual portions of movies and animations.
Visual-only Presentation: A visual-only presentation is content consisting exclusively of one or more visual tracks presented concurrently or in series. A silent movie is an example of a visual-only presentation.
Visual Track: A visual object is content rendered through a graphical viewport. Visual objects include graphics, text, and visual portions of movies and other animations. A visual track is a visual object that is intended as a whole or partial presentation. A visual track does not necessarily correspond to a single physical object or software object.
Vocabulary: A collection of attributes that adequately describe the CC-PP. A vocabulary is associated with a schema.
Voice Browser: From "Introduction and Overview of W3C Speech Interface Framework" VOICEBROWSER: "A voice browser is a device (hardware and software) that interprets voice markup languages to generate voice output, interpret voice input, and possibly accept and produce other modalities of input and output."; A device which interprets a (voice) markup language and is capable of generating voice output and/or interpreting voice input, and possibly other input/output modalities.; An assistive technology device. Voice browsers are systems which allow voice-driven navigation, some with both voice-input and voice-output, and some allowing telephone-based Web access.
W
Web Browsers (for Non-Visual Output): Blind and partially sighted people will use one of three possible methods to read pages on the World Wide Web. Users with some sight can use screen magnification software. For users with little or no useful sight the options are Speech Synthesizers or sound card to convert text into speech or a refreshable braille display to convert text into braille.
Web Resource: The term "Web resource" is used in accordance with Web Characterization Terminology and Definitions Sheet to mean anything that can be identified by a Uniform Resource Identifier (URI).
Web Services: A Web service is a software system identified by a URI, whose public interfaces and bindings are defined and described using XML. Its definition can be discovered by other software systems. These systems may then interact with the Web service in a manner prescribed by its definition, using XML based messages conveyed by Internet protocols.; A collection of EndPoints.
Web Site: A collection of interlinked Web pages, including a host page, residing at the same network location.
Word Breaks: Applications divide the text of a page into words; word breaks are the points in the text stream that separate adjoining words. Different applications may use different rules for defining words.
X
XML Schema: A language defined by the W3C for writing schemas which are both in and about XML, see http://www.w3.org/XML/Schema.
Y
Z

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