Rule Descriptions

WCAG 2.0 Level A & AA Rules

Rule ID	Description	Impact	Tags	Issue Type	ACT Rules
area-alt	Ensure <area> elements of image maps have alternative text	Critical	cat.text-alternatives, wcag2a, wcag244, wcag412, section508, section508.22.a, TTv5, TT6.a, EN-301-549, EN-9.2.4.4, EN-9.4.1.2, ACT, RGAAv4, RGAA-1.1.2	failure, needs review	c487ae
aria-allowed-attr	Ensure an element's role supports its ARIA attributes	Critical	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure, needs review	5c01ea
aria-braille-equivalent	Ensure aria-braillelabel and aria-brailleroledescription have a non-braille equivalent	Serious	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2	needs review
aria-command-name	Ensure every ARIA button, link and menuitem has an accessible name	Serious	cat.aria, wcag2a, wcag412, TTv5, TT6.a, EN-301-549, EN-9.4.1.2, ACT, RGAAv4, RGAA-11.9.1	failure, needs review	97a4e1
aria-conditional-attr	Ensure ARIA attributes are used as described in the specification of the element's role	Serious	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure	5c01ea
aria-deprecated-role	Ensure elements do not use deprecated roles	Minor	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure	674b10
aria-hidden-body	Ensure aria-hidden="true" is not present on the document body.	Critical	cat.aria, wcag2a, wcag131, wcag412, EN-301-549, EN-9.1.3.1, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure
aria-hidden-focus	Ensure aria-hidden elements are not focusable nor contain focusable elements	Serious	cat.name-role-value, wcag2a, wcag412, TTv5, TT6.a, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure, needs review	6cfa84
aria-input-field-name	Ensure every ARIA input field has an accessible name	Serious	cat.aria, wcag2a, wcag412, TTv5, TT5.c, EN-301-549, EN-9.4.1.2, ACT, RGAAv4, RGAA-11.1.1	failure, needs review	e086e5
aria-meter-name	Ensure every ARIA meter node has an accessible name	Serious	cat.aria, wcag2a, wcag111, EN-301-549, EN-9.1.1.1, RGAAv4, RGAA-11.1.1	failure, needs review
aria-progressbar-name	Ensure every ARIA progressbar node has an accessible name	Serious	cat.aria, wcag2a, wcag111, EN-301-549, EN-9.1.1.1, RGAAv4, RGAA-11.1.1	failure, needs review
aria-prohibited-attr	Ensure ARIA attributes are not prohibited for an element's role	Serious	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure, needs review	5c01ea
aria-required-attr	Ensure elements with ARIA roles have all required ARIA attributes	Critical	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure	4e8ab6
aria-required-children	Ensure elements with an ARIA role that require child roles contain them	Critical	cat.aria, wcag2a, wcag131, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-9.3.1	failure, needs review	bc4a75, ff89c9
aria-required-parent	Ensure elements with an ARIA role that require parent roles are contained by them	Critical	cat.aria, wcag2a, wcag131, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-9.3.1	failure	ff89c9
aria-roles	Ensure all elements with a role attribute use a valid value	Critical	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure	674b10
aria-toggle-field-name	Ensure every ARIA toggle field has an accessible name	Serious	cat.aria, wcag2a, wcag412, TTv5, TT5.c, EN-301-549, EN-9.4.1.2, ACT, RGAAv4, RGAA-7.1.1	failure, needs review	e086e5
aria-tooltip-name	Ensure every ARIA tooltip node has an accessible name	Serious	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2	failure, needs review
aria-valid-attr-value	Ensure all ARIA attributes have valid values	Critical	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure, needs review	6a7281
aria-valid-attr	Ensure attributes that begin with aria- are valid ARIA attributes	Critical	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure	5f99a7
blink	Ensure <blink> elements are not used	Serious	cat.time-and-media, wcag2a, wcag222, section508, section508.22.j, TTv5, TT2.b, EN-301-549, EN-9.2.2.2, RGAAv4, RGAA-13.8.1	failure
button-name	Ensure buttons have discernible text	Critical	cat.name-role-value, wcag2a, wcag412, section508, section508.22.a, TTv5, TT6.a, EN-301-549, EN-9.4.1.2, ACT, RGAAv4, RGAA-11.9.1	failure, needs review	97a4e1, m6b1q3
bypass	Ensure each page has at least one mechanism for a user to bypass navigation and jump straight to the content	Serious	cat.keyboard, wcag2a, wcag241, section508, section508.22.o, TTv5, TT9.a, EN-301-549, EN-9.2.4.1, RGAAv4, RGAA-12.7.1	needs review	cf77f2, 047fe0, b40fd1, 3e12e1, ye5d6e
color-contrast	Ensure the contrast between foreground and background colors meets WCAG 2 AA minimum contrast ratio thresholds	Serious	cat.color, wcag2aa, wcag143, TTv5, TT13.c, EN-301-549, EN-9.1.4.3, ACT, RGAAv4, RGAA-3.2.1	failure, needs review	afw4f7, 09o5cg
definition-list	Ensure <dl> elements are structured correctly	Serious	cat.structure, wcag2a, wcag131, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-9.3.3	failure
dlitem	Ensure <dt> and <dd> elements are contained by a <dl>	Serious	cat.structure, wcag2a, wcag131, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-9.3.3	failure
document-title	Ensure each HTML document contains a non-empty <title> element	Serious	cat.text-alternatives, wcag2a, wcag242, TTv5, TT12.a, EN-301-549, EN-9.2.4.2, ACT, RGAAv4, RGAA-8.5.1	failure	2779a5
duplicate-id-aria	Ensure every id attribute value used in ARIA and in labels is unique	Critical	cat.parsing, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-8.2.1	needs review	3ea0c8
form-field-multiple-labels	Ensure form field does not have multiple label elements	Moderate	cat.forms, wcag2a, wcag332, TTv5, TT5.c, EN-301-549, EN-9.3.3.2, RGAAv4, RGAA-11.2.1	needs review
frame-focusable-content	Ensure <frame> and <iframe> elements with focusable content do not have tabindex=-1	Serious	cat.keyboard, wcag2a, wcag211, TTv5, TT4.a, EN-301-549, EN-9.2.1.1, RGAAv4, RGAA-7.3.2	failure, needs review	akn7bn
frame-title-unique	Ensure <iframe> and <frame> elements contain a unique title attribute	Serious	cat.text-alternatives, wcag2a, wcag412, TTv5, TT12.d, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-2.2.1	needs review	4b1c6c
frame-title	Ensure <iframe> and <frame> elements have an accessible name	Serious	cat.text-alternatives, wcag2a, wcag412, section508, section508.22.i, TTv5, TT12.d, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-2.1.1	failure, needs review	cae760
html-has-lang	Ensure every HTML document has a lang attribute	Serious	cat.language, wcag2a, wcag311, TTv5, TT11.a, EN-301-549, EN-9.3.1.1, ACT, RGAAv4, RGAA-8.3.1	failure	b5c3f8
html-lang-valid	Ensure the lang attribute of the <html> element has a valid value	Serious	cat.language, wcag2a, wcag311, TTv5, TT11.a, EN-301-549, EN-9.3.1.1, ACT, RGAAv4, RGAA-8.4.1	failure	bf051a
html-xml-lang-mismatch	Ensure that HTML elements with both valid lang and xml:lang attributes agree on the base language of the page	Moderate	cat.language, wcag2a, wcag311, EN-301-549, EN-9.3.1.1, ACT, RGAAv4, RGAA-8.3.1	failure	5b7ae0
image-alt	Ensure <img> elements have alternative text or a role of none or presentation	Critical	cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a, TTv5, TT7.a, TT7.b, EN-301-549, EN-9.1.1.1, ACT, RGAAv4, RGAA-1.1.1	failure, needs review	23a2a8
input-button-name	Ensure input buttons have discernible text	Critical	cat.name-role-value, wcag2a, wcag412, section508, section508.22.a, TTv5, TT5.c, EN-301-549, EN-9.4.1.2, ACT, RGAAv4, RGAA-11.9.1	failure, needs review	97a4e1
input-image-alt	Ensure <input type="image"> elements have alternative text	Critical	cat.text-alternatives, wcag2a, wcag111, wcag412, section508, section508.22.a, TTv5, TT7.a, EN-301-549, EN-9.1.1.1, EN-9.4.1.2, ACT, RGAAv4, RGAA-1.1.3	failure, needs review	59796f
label	Ensure every form element has a label	Critical	cat.forms, wcag2a, wcag412, section508, section508.22.n, TTv5, TT5.c, EN-301-549, EN-9.4.1.2, ACT, RGAAv4, RGAA-11.1.1	failure, needs review	e086e5
link-in-text-block	Ensure links are distinguished from surrounding text in a way that does not rely on color	Serious	cat.color, wcag2a, wcag141, TTv5, TT13.a, EN-301-549, EN-9.1.4.1, RGAAv4, RGAA-10.6.1	failure, needs review
link-name	Ensure links have discernible text	Serious	cat.name-role-value, wcag2a, wcag244, wcag412, section508, section508.22.a, TTv5, TT6.a, EN-301-549, EN-9.2.4.4, EN-9.4.1.2, ACT, RGAAv4, RGAA-6.2.1	failure, needs review	c487ae
list	Ensure that lists are structured correctly	Serious	cat.structure, wcag2a, wcag131, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-9.3.1	failure
listitem	Ensure <li> elements are used semantically	Serious	cat.structure, wcag2a, wcag131, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-9.3.1	failure
marquee	Ensure <marquee> elements are not used	Serious	cat.parsing, wcag2a, wcag222, TTv5, TT2.b, EN-301-549, EN-9.2.2.2, RGAAv4, RGAA-13.8.1	failure
meta-refresh	Ensure <meta http-equiv="refresh"> is not used for delayed refresh	Critical	cat.time-and-media, wcag2a, wcag221, TTv5, TT8.a, EN-301-549, EN-9.2.2.1, RGAAv4, RGAA-13.1.2	failure	bc659a, bisz58
meta-viewport	Ensure <meta name="viewport"> does not disable text scaling and zooming	Moderate	cat.sensory-and-visual-cues, wcag2aa, wcag144, EN-301-549, EN-9.1.4.4, ACT, RGAAv4, RGAA-10.4.2	failure	b4f0c3
nested-interactive	Ensure interactive controls are not nested as they are not always announced by screen readers or can cause focus problems for assistive technologies	Serious	cat.keyboard, wcag2a, wcag412, TTv5, TT6.a, EN-301-549, EN-9.4.1.2, RGAAv4, RGAA-7.1.1	failure, needs review	307n5z
no-autoplay-audio	Ensure <video> or <audio> elements do not autoplay audio for more than 3 seconds without a control mechanism to stop or mute the audio	Moderate	cat.time-and-media, wcag2a, wcag142, TTv5, TT2.a, EN-301-549, EN-9.1.4.2, ACT, RGAAv4, RGAA-4.10.1	needs review	80f0bf
object-alt	Ensure <object> elements have alternative text	Serious	cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a, EN-301-549, EN-9.1.1.1, RGAAv4, RGAA-1.1.6	failure, needs review	8fc3b6
role-img-alt	Ensure [role="img"] elements have alternative text	Serious	cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a, TTv5, TT7.a, EN-301-549, EN-9.1.1.1, ACT, RGAAv4, RGAA-1.1.1	failure, needs review	23a2a8
scrollable-region-focusable	Ensure elements that have scrollable content are accessible by keyboard	Serious	cat.keyboard, wcag2a, wcag211, wcag213, TTv5, TT4.a, EN-301-549, EN-9.2.1.1, EN-9.2.1.3, RGAAv4, RGAA-7.3.2	failure	0ssw9k
select-name	Ensure select element has an accessible name	Critical	cat.forms, wcag2a, wcag412, section508, section508.22.n, TTv5, TT5.c, EN-301-549, EN-9.4.1.2, ACT, RGAAv4, RGAA-11.1.1	failure, needs review	e086e5
server-side-image-map	Ensure that server-side image maps are not used	Minor	cat.text-alternatives, wcag2a, wcag211, section508, section508.22.f, TTv5, TT4.a, EN-301-549, EN-9.2.1.1, RGAAv4, RGAA-1.1.4	needs review
summary-name	Ensure summary elements have discernible text	Serious	cat.name-role-value, wcag2a, wcag412, section508, section508.22.a, TTv5, TT6.a, EN-301-549, EN-9.4.1.2	failure, needs review
svg-img-alt	Ensure <svg> elements with an img, graphics-document or graphics-symbol role have accessible text	Serious	cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a, TTv5, TT7.a, EN-301-549, EN-9.1.1.1, ACT, RGAAv4, RGAA-1.1.5	failure, needs review	7d6734
td-headers-attr	Ensure that each cell in a table that uses the headers attribute refers only to other <th> elements in that table	Serious	cat.tables, wcag2a, wcag131, section508, section508.22.g, TTv5, TT14.b, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-5.7.4	failure, needs review	a25f45
th-has-data-cells	Ensure that <th> elements and elements with role=columnheader/rowheader have data cells they describe	Serious	cat.tables, wcag2a, wcag131, section508, section508.22.g, TTv5, TT14.b, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-5.7.1	failure, needs review	d0f69e
valid-lang	Ensure lang attributes have valid values	Serious	cat.language, wcag2aa, wcag312, TTv5, TT11.b, EN-301-549, EN-9.3.1.2, ACT, RGAAv4, RGAA-8.7.1	failure	de46e4
video-caption	Ensure <video> elements have captions	Critical	cat.text-alternatives, wcag2a, wcag122, section508, section508.22.a, TTv5, TT17.a, EN-301-549, EN-9.1.2.2, RGAAv4, RGAA-4.3.1	needs review	eac66b

WCAG 2.1 Level A & AA Rules

Rule ID	Description	Impact	Tags	Issue Type	ACT Rules
autocomplete-valid	Ensure the autocomplete attribute is correct and suitable for the form field	Serious	cat.forms, wcag21aa, wcag135, EN-301-549, EN-9.1.3.5, ACT, RGAAv4, RGAA-11.13.1	failure, needs review	73f2c2
avoid-inline-spacing	Ensure that text spacing set through style attributes can be adjusted with custom stylesheets	Serious	cat.structure, wcag21aa, wcag1412, EN-301-549, EN-9.1.4.12, ACT	failure	24afc2, 9e45ec, 78fd32

WCAG 2.2 Level A & AA Rules

These rules are disabled by default, until WCAG 2.2 is more widely adopted and required.

Rule ID	Description	Impact	Tags	Issue Type	ACT Rules
target-size	Ensure touch targets have sufficient size and space	Serious	cat.sensory-and-visual-cues, wcag22aa, wcag258	failure, needs review

Best Practices Rules

Rules that do not necessarily conform to WCAG success criterion but are industry accepted practices that improve the user experience.

Rule ID	Description	Impact	Tags	Issue Type	ACT Rules
accesskeys	Ensure every accesskey attribute value is unique	Serious	cat.keyboard, best-practice	failure
aria-allowed-role	Ensure role attribute has an appropriate value for the element	Minor	cat.aria, best-practice	failure, needs review
aria-dialog-name	Ensure every ARIA dialog and alertdialog node has an accessible name	Serious	cat.aria, best-practice	failure, needs review
aria-text	Ensure role="text" is used on elements with no focusable descendants	Serious	cat.aria, best-practice	failure, needs review
aria-treeitem-name	Ensure every ARIA treeitem node has an accessible name	Serious	cat.aria, best-practice	failure, needs review
empty-heading	Ensure headings have discernible text	Minor	cat.name-role-value, best-practice	failure, needs review	ffd0e9
empty-table-header	Ensure table headers have discernible text	Minor	cat.name-role-value, best-practice	failure, needs review
frame-tested	Ensure <iframe> and <frame> elements contain the axe-core script	Critical	cat.structure, best-practice, review-item	failure, needs review
heading-order	Ensure the order of headings is semantically correct	Moderate	cat.semantics, best-practice	failure, needs review
image-redundant-alt	Ensure image alternative is not repeated as text	Minor	cat.text-alternatives, best-practice	failure
label-title-only	Ensure that every form element has a visible label and is not solely labeled using hidden labels, or the title or aria-describedby attributes	Serious	cat.forms, best-practice	failure
landmark-banner-is-top-level	Ensure the banner landmark is at top level	Moderate	cat.semantics, best-practice	failure
landmark-complementary-is-top-level	Ensure the complementary landmark or aside is at top level	Moderate	cat.semantics, best-practice	failure
landmark-contentinfo-is-top-level	Ensure the contentinfo landmark is at top level	Moderate	cat.semantics, best-practice	failure
landmark-main-is-top-level	Ensure the main landmark is at top level	Moderate	cat.semantics, best-practice	failure
landmark-no-duplicate-banner	Ensure the document has at most one banner landmark	Moderate	cat.semantics, best-practice	failure
landmark-no-duplicate-contentinfo	Ensure the document has at most one contentinfo landmark	Moderate	cat.semantics, best-practice	failure
landmark-no-duplicate-main	Ensure the document has at most one main landmark	Moderate	cat.semantics, best-practice	failure
landmark-one-main	Ensure the document has a main landmark	Moderate	cat.semantics, best-practice	failure
landmark-unique	Ensure landmarks are unique	Moderate	cat.semantics, best-practice	failure
meta-viewport-large	Ensure <meta name="viewport"> can scale a significant amount	Minor	cat.sensory-and-visual-cues, best-practice	failure
page-has-heading-one	Ensure that the page, or at least one of its frames contains a level-one heading	Moderate	cat.semantics, best-practice	failure
presentation-role-conflict	Ensure elements marked as presentational do not have global ARIA or tabindex so that all screen readers ignore them	Minor	cat.aria, best-practice, ACT	failure	46ca7f
region	Ensure all page content is contained by landmarks	Moderate	cat.keyboard, best-practice, RGAAv4, RGAA-9.2.1	failure
scope-attr-valid	Ensure the scope attribute is used correctly on tables	Moderate	cat.tables, best-practice	failure
skip-link	Ensure all skip links have a focusable target	Moderate	cat.keyboard, best-practice, RGAAv4, RGAA-12.7.1	failure, needs review
tabindex	Ensure tabindex attribute values are not greater than 0	Serious	cat.keyboard, best-practice	failure
table-duplicate-name	Ensure the <caption> element does not contain the same text as the summary attribute	Minor	cat.tables, best-practice, RGAAv4, RGAA-5.2.1	failure, needs review

WCAG 2.x level AAA rules

Rules that check for conformance to WCAG AAA success criteria that can be fully automated. These are disabled by default in axe-core.

Rule ID	Description	Impact	Tags	Issue Type	ACT Rules
color-contrast-enhanced	Ensure the contrast between foreground and background colors meets WCAG 2 AAA enhanced contrast ratio thresholds	Serious	cat.color, wcag2aaa, wcag146, ACT	failure, needs review	09o5cg
identical-links-same-purpose	Ensure that links with the same accessible name serve a similar purpose	Minor	cat.semantics, wcag2aaa, wcag249	needs review	b20e66
meta-refresh-no-exceptions	Ensure <meta http-equiv="refresh"> is not used for delayed refresh	Minor	cat.time-and-media, wcag2aaa, wcag224, wcag325	failure	bisz58

Experimental Rules

Rules we are still testing and developing. They are disabled by default in axe-core, but are enabled for the axe browser extensions.

Rule ID	Description	Impact	Tags	Issue Type	ACT Rules
css-orientation-lock	Ensure content is not locked to any specific display orientation, and the content is operable in all display orientations	Serious	cat.structure, wcag134, wcag21aa, EN-301-549, EN-9.1.3.4, RGAAv4, RGAA-13.9.1, experimental	failure, needs review	b33eff
focus-order-semantics	Ensure elements in the focus order have a role appropriate for interactive content	Minor	cat.keyboard, best-practice, RGAAv4, RGAA-12.8.1, experimental	failure
hidden-content	Inform users about hidden content.	Minor	cat.structure, best-practice, experimental, review-item	failure, needs review
label-content-name-mismatch	Ensure that elements labelled through their content must have their visible text as part of their accessible name	Serious	cat.semantics, wcag21a, wcag253, EN-301-549, EN-9.2.5.3, RGAAv4, RGAA-6.1.5, experimental	failure	2ee8b8
p-as-heading	Ensure bold, italic text and font-size is not used to style <p> elements as a heading	Serious	cat.semantics, wcag2a, wcag131, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-9.1.3, experimental	failure, needs review
table-fake-caption	Ensure that tables with a caption use the <caption> element.	Serious	cat.tables, experimental, wcag2a, wcag131, section508, section508.22.g, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-5.4.1	failure
td-has-header	Ensure that each non-empty data cell in a <table> larger than 3 by 3 has one or more table headers	Critical	cat.tables, experimental, wcag2a, wcag131, section508, section508.22.g, TTv5, TT14.b, EN-301-549, EN-9.1.3.1, RGAAv4, RGAA-5.7.4	failure

Deprecated Rules

Deprecated rules are disabled by default and will be removed in the next major release.

Rule ID	Description	Impact	Tags	Issue Type	ACT Rules
aria-roledescription	Ensure aria-roledescription is only used on elements with an implicit or explicit role	Serious	cat.aria, wcag2a, wcag412, EN-301-549, EN-9.4.1.2, deprecated	failure, needs review
audio-caption	Ensure <audio> elements have captions	Critical	cat.time-and-media, wcag2a, wcag121, EN-301-549, EN-9.1.2.1, section508, section508.22.a, deprecated	needs review	2eb176, afb423
duplicate-id-active	Ensure every id attribute value of active elements is unique	Serious	cat.parsing, wcag2a-obsolete, wcag411, deprecated	failure	3ea0c8
duplicate-id	Ensure every id attribute value is unique	Minor	cat.parsing, wcag2a-obsolete, wcag411, deprecated	failure	3ea0c8

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