The GRUB graphical menu supports themes that can customize the layout andappearance of the GRUB boot menu. The theme is configured through a plaintext file that specifies the layout of the various GUI components (includingthe boot menu, timeout progress bar, and text messages) as well as theappearance using colors, fonts, and images. Example is available in docs/example_theme.txt
Content developers must consider these different situations during page design. While there are several situations to consider, each accessible design choice generally benefits several disability groups at once and the Web community as a whole. For example, by using style sheets to control font styles and eliminating the FONT element, HTML authors will have more control over their pages, make those pages more accessible to people with low vision, and by sharing the style sheets, will often shorten page download times for all users. The guidelines discuss accessibility issues and provide accessible design solutions. They address typical scenarios (similar to the font style example) that may pose problems for users with certain disabilities. For example, the first guideline explains how content developers can make images accessible. Some users may not be able to see images, others may use text-based browsers that do not support images, while others may have turned off support for images (e.g., due to a slow Internet connection). The guidelines do not suggest avoiding images as a way to improve accessibility. Instead, they explain that providing a text equivalent of the image will make it accessible. How does a text equivalent make the image accessible? Both words in "text equivalent" are important:
Font Creator 6.2 serial.13
Using markup improperly -- not according to specification --hinders accessibility. Misusing markup for a presentation effect(e.g., using a table for layout or a header to change the font size)makes it difficult for users with specializedsoftware to understand the organization of the page or tonavigate through it. Furthermore, using presentationmarkup rather than structural markup toconvey structure (e.g., constructing what looks like a table of datawith an HTML PRE element) makes it difficult to render a pageintelligibly to other devices (refer to the description ofdifference between content,structure, and presentation).
Content developersmay be tempted to use (or misuse) constructs that achieve adesired formatting effect on older browsers. They must be aware thatthese practices cause accessibility problems and must considerwhether the formatting effect is so critical as to warrantmaking the document inaccessible to some users.At the other extreme, content developers must not sacrificeappropriate markup because a certain browser or assistive technologydoes not process it correctly. For example, it is appropriate to usethe TABLE element in HTML to mark uptabular information eventhough some older screen readers may not handle side-by-sidetext correctly (refer to checkpoint 10.3). UsingTABLE correctly and creating tables that transform gracefully (refer toguideline 5) makes it possible for software to render tables otherthan as two-dimensional grids. Checkpoints:3.1 When an appropriate markup language exists, use markup rather than images to convey information. [Priority 2]For example, use MathML to mark up mathematicalequations, and style sheets to format text and control layout. Also,avoid using images to represent text -- use text and style sheetsinstead.Refer also to guideline 6 and guideline 11.Techniques for checkpoint 3.13.2 Create documents that validate to published formal grammars. [Priority 2]For example, include a document typedeclaration at the beginning of adocument that refers to a publishedDTD(e.g., the strict HTML 4.0 DTD).Techniques for checkpoint 3.23.3 Use style sheets to control layout and presentation. [Priority 2]For example, use the CSS 'font' propertyinstead of the HTML FONT element to control font styles.Techniques for checkpoint 3.33.4 Use relative rather than absolute units in markup language attribute values and style sheet property values. [Priority 2]For example, in CSS, use 'em' or percentagelengths rather than 'pt' or 'cm', which are absoluteunits. If absolute units are used,validate that the renderedcontent is usable (refer to thesection on validation).Techniques for checkpoint 3.43.5 Use header elements to convey document structure and use them according to specification. [Priority 2]For example, in HTML, use H2 to indicatea subsection of H1. Do not use headers for font effects.Techniques for checkpoint 3.53.6 Mark up lists and list items properly. [Priority 2]For example, in HTML, nest OL, UL, and DL lists properly.Techniques for checkpoint 3.63.7 Mark up quotations. Do not use quotation markup for formatting effects such as indentation. [Priority 2]For example, in HTML, use the Q and BLOCKQUOTE elementsto markup short and longer quotations, respectively.Techniques for checkpoint 3.7Guideline 4. Clarify natural language usage Use markup that facilitates pronunciation or interpretation ofabbreviated or foreign text.When content developers mark up natural language changes in adocument, speech synthesizers and braille devices can automaticallyswitch to the new language, making the document more accessibleto multilingual users.Content developers should identify the predominant natural language of a document'scontent (through markup orHTTP headers). Content developers shouldalso provide expansions of abbreviations and acronyms.In addition to helping assistive technologies, natural languagemarkup allows search engines to find key words and identify documentsin a desired language. Natural language markup also improvesreadability of the Web for all people, including those with learningdisabilities, cognitive disabilities, or people who are deaf.When abbreviations and natural language changes are not identified,they may be indecipherable when machine-spoken or brailled.
Note.Content developers should only resort to alternativepages when other solutions fail because alternative pagesare generally updated less often than "primary" pages. An out-of-datepage may be as frustrating as one that is inaccessible since, in bothcases, the information presented on the original page isunavailable. Automatically generating alternative pages may lead tomore frequent updates, but content developersmust still be careful to ensurethat generated pages always make sense, and that users are able tonavigate a site by following links on primary pages, alternativepages, or both. Before resorting to an alternative page,reconsider the design of the original page; making itaccessible is likely to improve it for all users.Guideline 12. Provide context and orientation information. Provide context and orientation information to help usersunderstand complex pages or elements.Grouping elements and providing contextual information about therelationships between elements can be useful for allusers. Complex relationships between parts of a page maybe difficult for people with cognitive disabilitiesand people with visual disabilities to interpret. Checkpoints:12.1 Title each frame to facilitate frame identification and navigation. [Priority 1]For example, in HTML use the "title" attribute on FRAMEelements.Techniques for checkpoint 12.112.2 Describe the purpose of frames and how frames relate to each other if it is not obvious by frame titles alone. [Priority 2]For example, in HTML, use "longdesc," or adescription link.Techniques for checkpoint 12.212.3 Divide large blocks of information into more manageable groups where natural and appropriate. [Priority 2]For example, in HTML, use OPTGROUPto group OPTION elements inside a SELECT;group form controls with FIELDSET and LEGEND;use nested lists where appropriate;use headings to structure documents, etc.Refer also to guideline 3.Techniques for checkpoint 12.312.4 Associate labels explicitly with their controls. [Priority 2]For example, in HTML use LABEL and its "for" attribute.Techniques for checkpoint 12.4Guideline 13. Provide clear navigation mechanisms. Provide clear and consistent navigation mechanisms --orientation information, navigation bars, a site map, etc. -- toincrease the likelihood that a person will find what they are lookingfor at a site.Clear and consistent navigationmechanisms are important to people with cognitivedisabilities or blindness, and benefit all users. Checkpoints:13.1 Clearly identify the target of each link. [Priority 2]Linktext should be meaningful enoughto make sense when read out of context --either on its own or as part of a sequence of links.Link text should also be terse.For example, in HTML, write "Information aboutversion 4.3" instead of "click here".In addition to clear link text, content developers mayfurther clarify the target of a linkwith an informative link title(e.g., in HTML, the "title" attribute).Techniques for checkpoint 13.113.2 Provide metadata to add semantic information to pages and sites. [Priority 2]For example, useRDF([RDF])to indicate the document's author,the type of content, etc.Note. Some HTML user agentscan build navigation tools from document relations described bythe HTML LINK element and "rel" or "rev" attributes(e.g., rel="next", rel="previous", rel="index", etc.).Refer also to checkpoint 13.5.Techniques for checkpoint 13.213.3 Provide information about the general layout of a site (e.g., a site map or table of contents). [Priority 2]In describing site layout,highlight and explain available accessibility features.Techniques for checkpoint 13.313.4 Use navigation mechanisms in a consistent manner. [Priority 2]Techniques for checkpoint 13.413.5 Provide navigation bars to highlight and give access to the navigation mechanism. [Priority 3]Techniques for checkpoint 13.513.6 Group related links, identify the group (for user agents), and, until user agents do so, provide a way to bypass the group. [Priority 3]Techniques for checkpoint 13.613.7 If search functions are provided, enable different types of searches for different skill levels and preferences. [Priority 3]Techniques for checkpoint 13.713.8 Place distinguishing information at the beginning of headings, paragraphs, lists, etc. [Priority 3]Note.This is commonly referred to as "front-loading" and isespecially helpful for people accessing information with serialdevices such as speech synthesizers.Techniques for checkpoint 13.813.9 Provide information about document collections (i.e., documents comprising multiple pages.). [Priority 3]For example, in HTMLspecify document collections with the LINKelement and the "rel" and "rev" attributes.Another way to create a collection is by buildingan archive (e.g., with zip, tar and gzip, stuffit, etc.)of the multiple pages.Note.The performance improvement gained by offlineprocessing can make browsing much lessexpensive for people with disabilities who maybe browsing slowly.Techniques for checkpoint 13.913.10 Provide a means to skip over multi-line ASCII art. [Priority 3]Refer to checkpoint 1.1 and the example of ascii artin the glossary.Techniques for checkpoint 13.10Guideline 14. Ensure that documentsare clear and simple. Ensure that documents are clear and simple sothey may be more easily understood.Consistent page layout, recognizable graphics, and easy to understandlanguage benefit all users. In particular, they helppeople with cognitive disabilities or whohave difficulty reading. (However, ensure that imageshave text equivalents for people who are blind, havelow vision, or for any user who cannot or haschosen not to view graphics. Refer also to guideline 1.)Using clear and simple language promotes effectivecommunication. Access to written information can be difficult forpeople who have cognitive or learning disabilities. Using clear andsimple language also benefits people whose first language differs fromyour own, including those people who communicate primarily in signlanguage. Checkpoints:14.1 Use the clearest and simplest language appropriate for a site's content. [Priority 1]Techniques for checkpoint 14.114.2 Supplement text with graphic or auditory presentations where they will facilitate comprehension of the page. [Priority 3]Refer also to guideline 1.Techniques for checkpoint 14.214.3 Create a style of presentation that is consistent across pages. [Priority 3]Techniques for checkpoint 14.3 Appendix A. -- ValidationValidate accessibility with automatic tools and humanreview. Automated methods are generally rapid and convenient but cannotidentify all accessibility issues. Human review can help ensureclarity of language and ease of navigation.Begin using validation methods at the earliest stages ofdevelopment. Accessibility issues identified early are easier tocorrect and avoid.Following are some important validation methods, discussed in moredetail in the sectionon validation in the Techniques Document.Use an automated accessibility tool and browser validation tool.Please note that software tools do not address all accessibilityissues, such as the meaningfulness of link text, the applicability ofa text equivalent, etc.
Validate syntax (e.g., HTML, XML, etc.).
Validate style sheets (e.g., CSS).
Use a text-only browser or emulator.
Use multiple graphic browsers, with:sounds and graphics loaded,graphics not loaded,sounds not loaded,no mouse,frames, scripts, style sheets, and applets not loaded
Use several browsers, old and new.
Use a self-voicingbrowser, a screen reader, magnification software, a small display,etc.
Use spell and grammar checkers. A person reading a page with aspeech synthesizer may not be able to decipher the synthesizer's bestguess for a word with a spelling error. Eliminating grammar problemsincreases comprehension.
Review the document for clarity and simplicity.Readability statistics, such as those generated by some wordprocessors may be useful indicators of clarity and simplicity. Betterstill, ask an experienced (human) editor to review written content forclarity. Editors can also improve the usability of documents byidentifying potentially sensitive cultural issuesthat might arise due to language or icon usage.Invite people with disabilities to review documents. Expertand novice users with disabilities will provide valuable feedbackabout accessibility or usability problems and their severity. Appendix B. -- Glossary AccessibleContent is accessible when it maybe used by someone with a disability.AppletA program inserted into a Web page.Assistive technologySoftware or hardware that has been specifically designed to assistpeople with disabilities in carrying out daily activities. Assistivetechnology includes wheelchairs, reading machines, devices forgrasping, etc. In the area of Web Accessibility, commonsoftware-based assistive technologies include screen readers, screenmagnifiers, speech synthesizers, and voice input software that operatein conjunction with graphical desktop browsers (among other useragents). Hardware assistive technologies includealternative keyboards and pointing devices.ASCII artASCII art refers to text characters and symbolsthat are combined to create an image. For example ";-)" is the smiley emoticon. The following isan ascii figure showing the relationship between flash frequency andphotoconvulsive response in patients witheyes open and closed [skipover ascii figure orconsult a descriptionof chart]: % __ __ __ __ __ __ __ __ __ __ __ __ __ __100 * 90 * * 80 * * 70 @ * 60 @ * 50 * @ * 40 @ * 30 * @ @ @ * 20 10 @ @ @ @ @ 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Flash frequency (Hertz)Authoring toolHTML editors, document conversion tools, tools thatgenerate Web content from databases are allauthoring tools. Refer to the"Authoring Tool Accessibility Guidelines" ([WAI-AUTOOLS]) for information about developingaccessible tools.Backward compatibleDesign that continues to work with earlier versionsof a language, program, etc.BrailleBraille uses six raised dots in different patterns to representletters and numbers to be read by people who are blind with theirfingertips. The word "Accessible" in braille follows:A braille display,commonly referred to as a "dynamic braille display," raises or lowersdot patterns on command from an electronic device, usually acomputer. The result is a line of braille that can change from momentto moment. Current dynamic braille displays range in size from one cell (sixor eight dots) to an eighty-cell line, most havingbetween twelve and twenty cells per line.ContentdeveloperSomeone who authors Web pages or designs Web sites.DeprecatedA deprecated element or attribute is one that has been outdated bynewer constructs. Deprecated elements may becomeobsolete in future versions of HTML. Theindex of HTML elements and attributes inthe Techniques Document indicates which elementsand attributes are deprecated in HTML 4.0.Authors should avoid using deprecated elements and attributes.User agents should continue to support forreasons of backward compatibility.Device independentUsers must be able to interact with a user agent(and the document it renders) using the supported input and outputdevices of their choice and according to their needs.Input devices may include pointing devices,keyboards, braille devices, head wands, microphones, andothers. Output devices may include monitors, speech synthesizers, andbraille devices.Please note that "device-independent support" does not mean thatuser agents must support every input or output device. User agentsshould offer redundant input and output mechanisms for those devicesthat are supported. For example, if a user agent supports keyboardand mouse input, users should be able to interact with all featuresusing either the keyboard or the mouse.Document Content,Structure, and PresentationThe content of a document refers towhat it says to the user through natural language,images, sounds, movies, animations, etc.The structure of a document is how it isorganized logically (e.g., by chapter, with anintroduction and table of contents, etc.).An element(e.g., P, STRONG, BLOCKQUOTE in HTML) that specifies documentstructure is called a structuralelement. The presentation of adocument is how the document is rendered (e.g., as print, as atwo-dimensional graphical presentation, as an text-only presentation,as synthesized speech, as braille, etc.)An elementthat specifies document presentation (e.g., B, FONT, CENTER)is called a presentationelement.Consider a document header, for example.The content of the header is whatthe header says (e.g., "Sailboats"). In HTML,the header is a structural elementmarked up with, for example, an H2 element.Finally, the presentation of the header might bea bold block text in the margin, a centered line of text,a title spoken with a certain voice style (like an auralfont), etc.DynamicHTML (DHTML)DHTML is the marketing term applied toa mixture of standards including HTML,style sheets, theDocument Object Model [DOM1]and scripting.However, there is no W3C specification that formally definesDHTML. Most guidelines may be applicableto applications using DHTML, however the following guidelines focus onissues related to scripting and style sheets: guideline 1,guideline 3, guideline 6,guideline 7, and guideline 9. ElementThis document uses the term "element" bothin the strict SGML sense (an element is a syntactic construct) andmore generally to mean a typeof content (such as video or sound) or a logicalconstruct (such as a header or list). The second senseemphasizes that a guideline inspired by HTMLcould easily apply to another markup language.Note that some (SGML) elements have content that is rendered(e.g., the P, LI, or TABLE elements in HTML), some are replacedby external content (e.g., IMG), and some affectprocessing (e.g., STYLE and SCRIPT cause informationto be processed by a style sheet or script engine).An element that causes text charactersto be part of the document is called a text element.EquivalentContent is "equivalent" to other content when both fulfill essentiallythe same function or purpose upon presentation to the user.In the context ofthis document, the equivalent must fulfill essentially the same functionfor the person with a disability (at least insofar as is feasible, giventhe nature of the disability and the state of technology), as the primarycontent does for the person without any disability.For example, the text "The Full Moon" might convey the same informationas an image of a full moon when presented to users. Note thatequivalent information focuses on fulfillingthe same function. If the image ispart of a link and understanding the image is crucialto guessing the link target, anequivalent must also give users an idea of the link target.Providing equivalent information for inaccessiblecontent is one of the primary waysauthors can make their documents accessible to people withdisabilities.As part of fulfilling the same function of contentan equivalent may involve a description of that content(i.e., what the content looks like or sounds like).For example, in order for users to understandthe information conveyed by a complex chart,authors should describe the visual information in the chart.Since text content can be presented to the user as synthesizedspeech, braille, and visually-displayed text, these guidelinesrequire textequivalents for graphic and audio information.Text equivalents must bewritten so that they convey all essential content.Non-textequivalents (e.g., anauditory description of a visual presentation, a video of a persontelling a story using sign language as anequivalent for a written story, etc.)also improve accessibility forpeople who cannot access visual informationor written text, including many individuals with blindness,cognitive disabilities, learning disabilities, and deafness.Equivalent information may be provided in a number of ways,including through attributes (e.g., a text value for the "alt"attribute in HTML and SMIL), as part of element content (e.g., theOBJECT in HTML), as part of the document's prose, or via a linkeddocument (e.g., designated by the "longdesc" attribute in HTML or a description link). Depending on the complexity ofthe equivalent, it may be necessary to combine techniques (e.g., use"alt" for an abbreviated equivalent, useful to familiar readers,in addition to "longdesc" for a link to more complete information,useful to first-time readers).The details of how and when to provide equivalent informationare part of the Techniques Document([TECHNIQUES]).A text transcriptis a text equivalent of audio information that includes spokenwords and non-spoken sounds such as sound effects.A caption is a texttranscript for the audio track of a video presentation that issynchronized with the video and audio tracks. Captions are generallyrendered visually by being superimposed over the video,which benefits people who are deaf andhard-of-hearing, and anyone who cannot hear the audio (e.g.,when in a crowded room).A collatedtext transcript combines (collates) captionswith text descriptions of video information(descriptions of the actions, body language, graphics, and scenechanges of the video track). These text equivalents makepresentations accessible to people who are deaf-blind and to people whocannot play movies, animations, etc. It also makes the informationavailable to search engines.One example of a non-text equivalent is an auditory descriptionof the key visual elements of a presentation.The description is either aprerecorded human voice or a synthesized voice (recorded or generatedon the fly). The auditory descriptionis synchronized with the audio track of the presentation, usuallyduring natural pauses in the audio track.Auditory descriptions include information about actions,body language, graphics, and scene changes.ImageA graphical presentation.Image mapAn image that has been divided into regions with associatedactions. Clicking on an active region causes an action to occur.When a user clicks on an active region of aclient-side image map,the user agent calculates in which region the click occurred andfollows the link associated with that region.Clicking on an activeregion of a server-side image map causes the coordinates of the clickto be sent to a server, which then performs some action.Content developerscan make client-side image maps accessible by providingdevice-independent access to the same links associated with the imagemap's regions. Client-side image maps allow the user agent to provideimmediate feedback as to whether or not the user's pointer is over anactive region.ImportantInformation in a documentis important if understanding that information iscrucial to understanding the document.Linearized tableA table rendering process where the contents ofthe cells become a series of paragraphs (e.g., downthe page) one after another. The paragraphs will occur in the sameorder as the cells are defined in the document source.Cells should make sense when read in order and shouldinclude structuralelements (that create paragraphs, headers, lists, etc.)so the page makes sense after linearization.Link textThe rendered text content of a link.NaturalLanguageSpoken, written, or signed human languages such as French,Japanese, American Sign Language, and braille.The natural language of content maybe indicated with the "lang" attribute in HTML ([HTML40], section 8.1)and the "xml:lang"attribute in XML ([XML], section 2.12).Navigation MechanismA navigation mechanism is any means by which a user cannavigate a page or site. Some typical mechanisms include:navigation barsA navigation bar is a collection of linksto the most important parts of a document or site.site maps A site map provides a global view of theorganization of a page or site.tables of contents A table of contents generally lists(and links to) the most important sections of a document.Personal Digital Assistant(PDA)A PDA is a small,portable computing device. Most PDAs are used to track personal datasuch as calendars, contacts, and electronic mail. A PDA is generally ahandheld device with a small screen that allows input from varioussources.ScreenmagnifierA software program that magnifies a portion of the screen, sothat it can be more easily viewed. Screen magnifiersare used primarily by individualswith low vision.Screen readerA software program that reads the contents of the screen aloudto a user. Screen readers are used primarilyby individuals who are blind. Screenreaders can usually only read text that is printed, not painted, tothe screen.Style sheetsA style sheet is a set of statements that specify presentation ofa document. Style sheets may have three different origins: theymay be written by content providers, created by users, orbuilt into user agents. In CSS ([CSS2]),the interaction of content provider, user, and user agentstyle sheets is called the cascade.Presentation markupis markup that achieves a stylistic (rather than structuring) effectsuch as the B or I elements in HTML. Note that the STRONG and EMelements are not considered presentation markup since they conveyinformation that is independent of a particular font style.Tabular informationWhen tables are used to represent logical relationships amongdata -- text, numbers, images, etc., that information iscalled "tabular information" and the tables arecalled "data tables". The relationships expressed by a tablemay be rendered visually (usually on a two-dimensional grid),aurally (often preceding cells with header information),or in other formats.Until user agents ...In most of the checkpoints, content developers are asked toensure the accessibility of their pages and sites. However, there areaccessibility needs that would be more appropriately met byuseragents (includingassistive technologies).As of the publication ofthis document, not all user agents orassistive technologies provide the accessibility control users require(e.g., some user agents may not allow users to turn off blinkingcontent, or some screen readers may not handle tables well).Checkpoints that contain the phrase "until user agents ..." requirecontent developers to provide additional support for accessibilityuntil most user agents readily available to theiraudience include the necessary accessibility features.Note. The W3C WAI Web site(refer to [WAI-UA-SUPPORT])provides informationabout user agent support for accessibility features.Content developers are encouraged to consult this pageregularly for updated information.Useragent Software to access Webcontent, including desktop graphical browsers, text browsers, voicebrowsers, mobile phones, multimedia players, plug-ins, and somesoftware assistive technologies used in conjunction with browsers such asscreen readers, screen magnifiers, and voice recognition software. AcknowledgmentsWeb Content Guidelines Working Group Co-Chairs:Chuck Letourneau,Starling Access ServicesGregg Vanderheiden,Trace Research and DevelopmentW3C Team contacts:Judy Brewer and Daniel DardaillerWe wish to thank the following people who have contributed theirtime and valuable comments to shaping these guidelines:Harvey Bingham, Kevin Carey, Chetz Colwell, Neal Ewers, GeoffFreed, Al Gilman, Larry Goldberg, Jon Gunderson, Eric Hansen,Phill Jenkins, LeonardKasday, George Kerscher, Marja-Riitta Koivunen, Josh Krieger, ScottLuebking, William Loughborough, Murray Maloney, CharlesMcCathieNevile, MegaZone (Livingston Enterprises), Masafumi Nakane,Mark Novak, Charles Oppermann, Mike Paciello, David Pawson, Michael Pieper,Greg Rosmaita, Liam Quinn, Dave Raggett, T.V. Raman, RobertSavellis, Jutta Treviranus, Steve Tyler, Jaap van Lelieveld, andJason WhiteThe original draft of this document is based on "The Unified WebSite Accessibility Guidelines" ([UWSAG])compiled by the Trace R & D Center at the University of Wisconsin.That document includes a list of additional contributors. ReferencesFor the latest version of any W3C specification please consult thelist of W3C Technical Reports.
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