A “bdo” element must have a “dir” attribute. An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images. http://www.w3.org/wiki/HTML/Usage/TextAlternatives The “” element must not contain any nested “” elements. The “” element must not contain any nested “” elements. The “label” element may contain at most one descendant “input” element, “button” element, “select” element, or “textarea” element. The “for” attribute of the “label” element must refer to a form control. The sectioning element “” must not appear as a descendant of the “address” element. The element “footer” must not appear as a descendant of the “header” element. The element “footer” must not appear as a descendant of the “footer” element. The element “footer” must not appear as a descendant of the “address” element. The “” element must not appear as a descendant of the “address” element. The “” element must not appear as a descendant of the “footer” element. The “” element must not appear as a descendant of the “address” element. The “header” element must not appear as a descendant of the “header” element. The element “table” must not appear as a descendant of the “caption” element. The “summary” attribute on the “table” element is obsolete. Consider describing the structure of the table in a “caption” element or in a “figure” element containing the “table” element; or, simplify the structue of the table so that no description is needed. The interactive element “” must not appear as a descendant of the “a” element. The interactive element “” must not appear as a descendant of the “button” element. The interactive element “” must not appear as a descendant of the “a” element. The interactive element “” must not appear as a descendant of the “button” element. Any “” element descendant of a “label” element with a “for” attribute must have an ID value that matches that “for” attribute. The interactive element “” with the attribute “controls” must not appear as a descendant of the “a” element. The interactive element “” with the attribute “controls” must not appear as a descendant of the “button” element. The element “menu” with the attribute “type” whose value is “toolbar” must not appear as a descendant of the “a” element. The element “menu” with the attribute “type” whose value is “toolbar” must not appear as a descendant of the “button” element. The element “img” with the attribute “usemap” must not appear as a descendant of the “a” element. The element “img” with the attribute “usemap” must not appear as a descendant of the “button” element. The element “object” with the attribute “usemap” must not appear as a descendant of the “a” element. The element “object” with the attribute “usemap” must not appear as a descendant of the “button” element. The “area” element must have an ancestor “map” element. The “img” element with the “ismap” attribute set must have an ancestor “a” element with the “href” attribute. The “list” attribute of the “input” element must refer to a “datalist” element. Element “input” with attribute “type” whose value is “button” must have non-empty attribute “value”. Attribute “label” for element “track” must have non-empty value. The “default” attribute must not occur on more than one “track” element within the same “audio” element or “video” element. The “id” attribute on a “map” element must have the same value as the “name” attribute. The “select” element cannot have more than one selected “option” element descendant unless the “multiple” attribute is specified. A “select” element with a “required” attribute and without a “multiple” attribute, and whose size is “1”, must have a child “option” element. The first child “option” element of a “select” element with a “required” attribute and without a “multiple” attribute, and whose size is “1”, must have either an empty “value” attribute, or must have no text content. Element “script” with attribute “language” whose value is “JavaScript” must not have attribute “type” whose value is not “text/javascript”. Element “script” must not have attribute “charset” unless attribute “src” is also specified. Element “script” must not have attribute “defer” unless attribute “src” is also specified. Element “script” must not have attribute “async” unless attribute “src” is also specified. The element “time” must not appear as a descendant of the “time” element. The element “progress” must not appear as a descendant of the “progress” element. The value of the “value” attribute must be less than or equal to the value of the “max” attribute. The value of the “value” attribute must be less than or equal to one when the “max” attribute is absent. The element “meter” must not appear as a descendant of the “meter” element. The value of the “min” attribute must be less than or equal to the value of the “value” attribute. The value of the “value” attribute must be greater than or equal to zero when the “min” attribute is absent. The value of the “value” attribute must be less than or equal to the value of the “max” attribute. The value of the “value” attribute must be less than or equal to one when the “max” attribute is absent. The value of the “min” attribute must be less than or equal to the value of the “max” attribute. The value of the “max” attribute must be greater than or equal to zero when the “min” attribute is absent. The value of the “min” attribute must be less than or equal to one when the “max” attribute is absent. The value of the “min” attribute must be less than or equal to the value of the “low” attribute. The value of the “low” attribute must be greater than or equal to zero when the “min” attribute is absent. The value of the “min” attribute must be less than or equal to the value of the “high” attribute. The value of the “high” attribute must be greater than or equal to zero when the “min” attribute is absent. The value of the “low” attribute must be less than or equal to the value of the “high” attribute. The value of the “high” attribute must be less than or equal to the value of the “max” attribute. The value of the “high” attribute must be less than or equal to one when the “max” attribute is absent. The value of the “low” attribute must be less than or equal to the value of the “max” attribute. The value of the “low” attribute must be less than or equal to one when the “max” attribute is absent. The value of the “min” attribute must be less than or equal to the value of the “optimum” attribute. The value of the “optimum” attribute must be greater than or equal to zero when the “min” attribute is absent. The value of the “optimum” attribute must be less than or equal to the value of the “max” attribute. The value of the “optimum” attribute must be less than or equal to one when the “max” attribute is absent. The “acronym” element is obsolete. Use the “abbr” element instead. The “applet” element is obsolete. Use the “object” element instead. The “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “dir” element is obsolete. Use the “ul” element instead. The “” element is obsolete. Use the “iframe” element and CSS instead, or use server-side includes. The “coords” attribute on the “” element is obsolete. For image maps, use the “area” element instead of the “a” element. The “shape” attribute on the “” element is obsolete. For image maps, use the “area” element instead of the “a” element. The “urn” attribute on the “” element is obsolete. Specify the preferred persistent identifier using the “href” attribute instead. The “charset” attribute on the “” element is obsolete. Use an HTTP Content-Type header on the linked resource instead. The “methods” attribute on the “” element is obsolete. Use the HTTP OPTIONS feature instead. The “rev” attribute on the “” element is obsolete. Use the “rel” attribute instead, with a term having the opposite meaning. The “target” attribute on the “” element is obsolete. You can safely omit it. The “urn” attribute on the “” element is obsolete. Specify the preferred persistent identifier using the “href” attribute instead. The “charset” attribute on the “” element is obsolete. Use an HTTP Content-Type header on the linked resource instead. The “methods” attribute on the “” element is obsolete. Use the HTTP OPTIONS feature instead. The “rev” attribute on the “” element is obsolete. Use the “rel” attribute instead, with a term having the opposite meaning. The “nohref” attribute on the “” element is obsolete. Omitting the “href” attribute is sufficient. The “name” attribute on the “” element is obsolete. Use the “id” attribute instead. The “profile” attribute on the “” element is obsolete. To declare which “meta” element terms are used in the document, instead register the names as meta extensions. <http://wiki.whatwg.org/wiki/MetaExtensions> To trigger specific UA behaviors, use a “link” element instead. The “version” attribute on the “” element is obsolete. You can safely omit it. The “longdesc” attribute on the “” element is obsolete. Use a regular “a” element to link to the description. The “longdesc” attribute on the “” element is obsolete. Use a regular “a” element to link to the description. The “name” attribute on the “” element is obsolete. Use the “id” attribute instead. The “usemap” attribute on the “” element is obsolete. Use the “img” element instead of the “input” element for image maps. The “type” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “scheme” attribute on the “” element is obsolete. Use only one scheme per field, or make the scheme declaration part of the value. Using the “meta” element to specify the document-wide default language is obsolete. Consider specifying the language on the root element instead. The “archive” attribute on the “” element is obsolete. Use the “data” attribute and “type” attribute to invoke plugins. To set a parameter with the name “archive”, use the “param” element. The “classid” attribute on the “” element is obsolete. Use the “data” attribute and “type” attribute to invoke plugins. To set a parameter with the name “classid”, use the “param” element. The “code” attribute on the “” element is obsolete. Use the “data” attribute and “type” attribute to invoke plugins. To set a parameter with the name “code”, use the “param” element. The “codebase” attribute on the “” element is obsolete. Use the “data” attribute and “type” attribute to invoke plugins. To set a parameter with the name “codebase”, use the “param” element. The “codetype” attribute on the “” element is obsolete. Use the “data” attribute and “type” attribute to invoke plugins. To set a parameter with the name “codetype”, use the “param” element. The “declare” attribute on the “” element is obsolete. Repeat the “object” element completely each time the resource is to be reused. The “standby” attribute on the “” element is obsolete. Optimize the linked resource so that it loads quickly or, at least, incrementally. The “name” attribute on the “” element is obsolete. Use the “id” attribute instead. The “type” attribute on the “” element is obsolete. Use the “name” attribute and “value” attribute without declaring value types. The “valuetype” attribute on the “” element is obsolete. Use the “name” attribute and “value” attribute without declaring value types. The “language” attribute on the “script” element is obsolete. Use the “type” attribute instead. The “scope” attribute on the “td” element is obsolete. Use the “scope” attribute on a “th” element instead. The “abbr” attribute on the “” element is obsolete. Consider instead beginning the cell contents with concise text, followed by further elaboration if needed. The “axis” attribute on the “” element is obsolete. Use the “scope” attribute instead. The “align” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “width” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “char” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “charoff” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “valign” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “alink” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “background” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “bgcolor” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “link” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “marginbottom” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “marginheight” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “marginleft” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “marginright” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “margintop” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “marginwidth” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “text” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “vlink” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “clear” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “hspace” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “vspace” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “noshade” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “size” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “color” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “compact” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “allowtransparency” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “frameborder” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “marginheight” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “marginwidth” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “scrolling” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “hspace” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “vspace” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “border” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “bgcolor” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The value of the “border” attribute on the “” element must be either “1” or the empty string. To regulate the thickness of table borders, Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “cellpadding” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “cellspacing” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “frame” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “rules” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “bgcolor” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “height” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “nowrap” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes The “bgcolor” attribute on the “” element is obsolete. Use CSS instead. http://wiki.whatwg.org/wiki/Presentational_elements_and_attributes When the attribute “lang” in no namespace and the attribute “lang” in the XML namespace are both present, they must have the same value. The “contextmenu” attribute must refer to a “menu” element. An element with “role=option” requires “role=listbox” on the parent. An element with “role=menuitem” requires “role=menu” on the parent. An element with “role=menuitemcheckbox” requires “role=menu” on the parent. An element with “role=menuitemradio” requires “role=menu” on the parent. An element with “role=tab” requires “role=tablist” on the parent. An element with “role=treeitem” requires “role=tree” on the parent. An element with “role=listitem” requires “role=list” on the parent. An element with “role=row” requires “role=treegrid” or “role=grid” on the parent or grandparent. An element with “role=gridcell” requires “role=row” on the parent. An element must not be a child of “role=listbox” unless it has “role=option”. An element must not be a child of “role=menu” unless it has “role=menuitem”, “role=menuitemcheckbox” or “role=menuitemradio”. An element must not be a child of “role=tree” unless it has “role=treeitem”. An element must not be a child of “role=list” unless it has “role=listitem”. An element must not be a child of “role=radiogroup” unless it has “role=radio”. An element must not be a child of “role=row” unless it has “role=gridcell”. An element must not be a child of “role=tablist” unless it has “role=role”. The “aria-activedescendant” attribute must refer to a descendant element. The “aria-controls” attribute must point to an element in the same document. The “aria-describedby” attribute must point to an element in the same document. The “aria-flowto” attribute must point to an element in the same document. The “aria-labelledby” attribute must point to an element in the same document. The “aria-owns” attribute must point to an element in the same document. The “border” attribute on the “img” element is obsolete. Consider specifying “img { border: 0; }“ in CSS instead. The “language” attribute on the “script” element is obsolete. You can safely omit it. The “name” attribute on the “a” element is obsolete. Consider putting an “id” attribute on the nearest container instead. “” element has more than one “track” child element with a “default” attribute.