<?xml version="1.0" encoding="ISO-8859-1"?>
<book xmlns:un="http://usablenet.com/namespaces/508_rules" name="UsableNet Accessibility Reference" module_location="referenceAPI.htm" language="Accessibility"><topic_title name="规则"/><subtopic_title name="Rule Description Section"/><default location="default.htm"/><topic name="Non spacer IMG with valid ALT" location="nspIMGwValidALT.htm" id="Description">&nbsp;</topic><topic name="Spacer IMG with valid ALT" location="spIMGwValidALT.htm" id="Description">&nbsp;</topic><topic name="Non spacer IMG with equivalent ALT" location="nspIMGwEquivalentALT.htm" id="Description">&nbsp;</topic><topic name="Non spacer IMG with valid LONGDESC" location="nspIMGwValidLongdesc.htm" id="Description">&nbsp;</topic><topic name="No LONGDESC for spacer IMG" location="spIMGwNoLongdesc.htm" id="Description">&nbsp;</topic><topic name="Non spacer IMG needs LONGDESC" location="nspIMGneedsLongdesc.htm" id="Description">&nbsp;</topic><topic name="INPUT with valid ALT" location="INPUTwValidALT.htm" id="Description">&nbsp;</topic><topic name="INPUT with equivalent ALT" location="INPUTwEquivalentALT.htm" id="Description">&nbsp;</topic><topic name="FRAME with valid LONGDESC" location="FRAMEwValidLongdesc.htm" id="Description">&nbsp;</topic><topic name="SCRIPT with valid NOSCRIPT" location="SCRIPTwValidNOSCRIPT.htm" id="Description">&nbsp;</topic><topic name="SCRIPT with equivalent NOSCRIPT" location="SCRIPTwEquivalentNOSCRIPT.htm" id="Description">&nbsp;</topic><topic name="AREA with valid ALT" location="AREAwValidALT.htm" id="Description">&nbsp;</topic><topic name="AREA with equivalent ALT" location="AREAwEquivalentALT.htm" id="Description">&nbsp;</topic><topic name="Color is not essential" location="DontRelyOnColorAlone.htm" id="Description">&nbsp;</topic><topic name="Colors are visible" location="ColorsAreVisible.htm" id="Description">&nbsp;</topic><topic name="Style sheets should not be necessary" location="StyleSheetsNotNecessary.htm" id="Description">&nbsp;</topic><topic name="Links are needed for server-side image map" location="RdndtLnksSSimagemap.htm" id="Description">&nbsp;</topic><topic name="No server-side image maps should be used" location="NoServerSideImageMaps.htm" id="Description">&nbsp;</topic><topic name="Data table should have headers" location="TableWithHeaders.htm" id="Description">&nbsp;</topic><topic name="Cell of data table should refer to headers" location="CellsReferToHeaders.htm" id="Description">&nbsp;</topic><topic name="Data tables should be defined by TABLE tag" location="PREisNotATable.htm" id="Description">&nbsp;</topic><topic name="Multiple headers should be marked in data tables" location="TABLEwithMultipleLevels.htm" id="Description">&nbsp;</topic><topic name="FRAME with valid TITLE" location="FRAMEwValidTitle.htm" id="Description">&nbsp;</topic><topic name="IFRAME with valid TITLE" location="IFRAMEwValidTitle.htm" id="Description">&nbsp;</topic><topic name="Text only equivalent page may be needed" location="TextOnlyEquivPage.htm" id="Description">&nbsp;</topic><topic name="Scripts are accessible" location="AccessibleScripts.htm" id="Description">&nbsp;</topic><topic name="Link to plug-in is present" location="LinkToPluginIsPresent.htm" id="Description">&nbsp;</topic><topic name="APPLET with valid ALT" location="APPLETwValidALT.htm" id="Description">&nbsp;</topic><topic name="APPLET with equivalent ALT" location="APPLETwEquivalentALT.htm" id="Description">&nbsp;</topic><topic name="APPLET with valid CONTENT" location="APPLETwValidCONTENT.htm" id="Description">&nbsp;</topic><topic name="Form is accessible" location="FormIsAccessible.htm" id="Description">&nbsp;</topic><topic name="Skip repetitive links" location="SkipRepetitiveLinks.htm" id="Description">&nbsp;</topic><topic name="No javascript links are used" location="NoJavascriptLinks.htm" id="Description">&nbsp;</topic><topic name="No auto refresh is used" location="NoRefreshIsUsed.htm" id="Description">&nbsp;</topic><topic name="No auto redirect is used" location="NoRedirectIsUsed.htm" id="Description">&nbsp;</topic><topic name="GIFs do not cause the screen to flicker" location="NoFlickeringGIFs.htm" id="Description">&nbsp;</topic><topic name="Avoid causing the screen to flicker" location="NoFlickeringObjects.htm" id="Description">&nbsp;</topic><topic name="Image OBJECT with valid CONTENT" location="imgOBJECTwValidContent.htm" id="Description">&nbsp;</topic><topic name="Image OBJECT with equivalent CONTENT" location="imgOBJwEquivCont.htm" id="Description">&nbsp;</topic><topic name="Audio/video OBJECT with valid CONTENT" location="avOBJECTwValidContent.htm" id="Description">&nbsp;</topic><topic name="Audio/video OBJECT with equivalent CONTENT" location="avOBJwEquivContent.htm" id="Description">&nbsp;</topic><topic name="OBJECT with valid CONTENT" location="OBJECTwValidContent.htm" id="Description">&nbsp;</topic><topic name="OBJECT with equivalent CONTENT" location="OBJECTwEquivalentContent.htm" id="Description">&nbsp;</topic><topic name="Multimedia with synchronized alternative" location="MuMediawSynchAlt.htm" id="Description">&nbsp;</topic><topic name="Multimedia with equivalent audio description" location="MmediaEquivAuDescr.htm" id="Description">&nbsp;</topic><topic name="Use clear language for site's content" location="ClearLangForSite.htm" id="Description">&nbsp;</topic><topic name="Clarify natural language usage" location="ClarifyNatLangUsage.htm" id="Description">&nbsp;</topic><topic name="Linked AUDIO with equivalent CONTENT" location="linkedAUDIOwEquivContent.htm" id="Description">&nbsp;</topic><topic name="Proprietary tags are used" location="proprietaryTagsAreUsed.htm" id="Description">&nbsp;</topic><topic name="Ensure sufficient contrast between foreground and background colors" location="fgColOverBgCol.htm" id="Description">&nbsp;</topic><topic name="Use markup rather than images" location="mrkpRtImg.htm" id="Description">&nbsp;</topic><topic name="Document should be valid with respect to published grammars" location="docValFrmGrm.htm" id="Description">&nbsp;</topic><topic name="Use a public text identifier in a DOCTYPE statement" location="publicDoctype.htm" id="Description">&nbsp;</topic><topic name="Use style sheets" location="SSCtrlLyPr.htm" id="Description">&nbsp;</topic><topic name="Use percentage values for frame sizes" location="frameSize.htm" id="Description">&nbsp;</topic><topic name="Use percentage values for table sizes" location="tableSize.htm" id="Description">&nbsp;</topic><topic name="Use relative units in CSS" location="relThAbsUnitMrkpSS.htm" id="Description">&nbsp;</topic><topic name="Use relative units in CSS box properties" location="relThAbsUnitMrkpSSBox.htm" id="Description">&nbsp;</topic><topic name="Use header elements" location="useHeaders.htm" id="Description">&nbsp;</topic><topic name="Use header elements according to specification" location="hdElAccSpec.htm" id="Description">&nbsp;</topic><topic name="Properly mark up lists and related items" location="mrkLstItmPrp.htm" id="Description">&nbsp;</topic><topic name="Mark up quotations" location="mrkpQuot.htm" id="Description">&nbsp;</topic><topic name="Avoid using quotation markup for formatting effects" location="noQtMrkpFrmEff.htm" id="Description">&nbsp;</topic><topic name="Layout tables should make sense when linearized" location="linTbUseLyNoSs.htm" id="Description">&nbsp;</topic><topic name="Avoid using structural markup for visual formatting" location="noStrMrkpVslFrmTbLy.htm" id="Description">&nbsp;</topic><topic name="Use device-independent event handlers" location="inptDevIndEvHndScrApl.htm" id="Description">&nbsp;</topic><topic name="Avoid JavaScript links" location="noJSLinks.htm" id="Description">&nbsp;</topic><topic name="FRAMESET should have valid NOFRAMES" location="validNOFRAMES.htm" id="Description">&nbsp;</topic><topic name="Dynamic content should be accessible" location="dynCntAcc.htm" id="Description">&nbsp;</topic><topic name="Avoid causing content to blink" location="avdCsgCntBlk.htm" id="Description">&nbsp;</topic><topic name="Avoid objects that may cause the screen to blink" location="avdElmScrBlk.htm" id="Description">&nbsp;</topic><topic name="GIFs should not cause the screen to blink" location="gifNoScrBlk.htm" id="Description">&nbsp;</topic><topic name="GIFs should not cause movement" location="gifNoMvmPg.htm" id="Description">&nbsp;</topic><topic name="Objects should not cause movement" location="objNoMvmPg.htm" id="Description">&nbsp;</topic><topic name="Avoid MARQUEE elements" location="avoidMarquee.htm" id="Description">&nbsp;</topic><topic name="Avoid auto-refreshing pages" location="avdAutRfrPg.htm" id="Description">&nbsp;</topic><topic name="Avoid redirecting pages by markup" location="avdRedPgMarkp.htm" id="Description">&nbsp;</topic><topic name="Jump menu should be device-independent" location="JmpMenu.htm" id="Description">&nbsp;</topic><topic name="Objects should have device-independent interface" location="elmOwnIntfDecIndp.htm" id="Description">&nbsp;</topic><topic name="Specify logical event handlers" location="spcLgcRtDDEvHndScr.htm" id="Description">&nbsp;</topic><topic name="Inform users if new windows appear" location="winAppWttInfUsr.htm" id="Description">&nbsp;</topic><topic name="Inform users if pop-up windows appear" location="popAppWttInfUsr.htm" id="Description">&nbsp;</topic><topic name="Properly position implicit labels in forms" location="implAssLblFrmCtrlPrPos.htm" id="Description">&nbsp;</topic><topic name="Use last appropriate W3C technologies" location="useLstW3CTch.htm" id="Description">&nbsp;</topic><topic name="Avoid deprecated features of W3C technologies" location="avdDepFtW3CTch.htm" id="Description">&nbsp;</topic><topic name="Describe frames and their relationship" location="dscFrmRlshTtNoClr.htm" id="Description">&nbsp;</topic><topic name="FRAME should have valid LONGDESC" location="FRAME_vLDESC.htm" id="Description">&nbsp;</topic><topic name="Divide information into appropriate manageable groups" location="dvdInfAppMngGrp.htm" id="Description">&nbsp;</topic><topic name="Add explicit labels to form controls" location="assLblExpCtrl.htm" id="Description">&nbsp;</topic><topic name="Clearly identify the target of each link" location="clrIdtTrgLnk.htm" id="Description">&nbsp;</topic><topic name="Use meaningful labels for links" location="useMngLblLnk.htm" id="Description">&nbsp;</topic><topic name="Do not use the same link phrase more than once when the links point to different URLs" location="sameLnkDiffUrls.htm" id="Description">&nbsp;</topic><topic name="Provide metadata to pages and sites" location="prvMtdtPgSt.htm" id="Description">&nbsp;</topic><topic name="Page title should be well defined" location="validPageTitle.htm" id="Description">&nbsp;</topic><topic name="Provide information about site organization" location="prvInfGnrLytSt.htm" id="Description">&nbsp;</topic><topic name="Use navigation mechanisms appropriately" location="useNvgMchApp.htm" id="Description">&nbsp;</topic></book>