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Vestby

Screen reader users will see links on a page listed without context, 
so you should ensure the same link text is not used to point to different web
addresses.

For example:

```html
<p>
    Learn the latest about our products: 
    <a href="/products/news">News</a>
</p>

<p>
    Learn the latest about our services: 
    <a href="/company/news">News</a>
</p>
``` 

To a screen reader who is listing links, they will only hear:

* News
* News

These links appear to be the same, but they both behave differently. 
One solution, which doesn't require the page design to change, is to add an 
`aria-label` for each link:

```html
<p>
    Learn the latest about our products: 
    <a href="/products/news" aria-label="Product news">News</a>
</p>

<p>
    Learn the latest about our services: 
    <a href="/company/news" aria-label="Company news">News</a>
</p>
``` 

Which will be heard as:

* Product news
* Company news

To pass this checkpoint, make sure that links which point to different pages 
have distinct text inside them, or that they specify ARIA labels (`aria-labelledby` or
`aria-label`), or they use hidden text only visible to screen readers
(e.g. `<span class="sr-only">...</span>`) to distinguish them from each 
other.

If links point to the same page (e.g., they redirect or use tracking
parameters, but are functionally equivalent to the user) you can ignore
this issue.

a-duplicate-link-text-for-different-destinations

To comply with the strictest accessibility standard (WCAG AAA), the colour of text must 
strongly contrast with its background color, so that people with significant visual impairments 
can read it.

The [contrast ratio](https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html#contrast-ratiodef)
must be at least 7:1 for body text, and 4.5:1 for large text.

A far less demanding version of this check (1.4.3) exists for WCAG AA. All websites should aim to 
meet the easier AA standard at a minimum. The AAA standard is desirable but far more challenging,
and may not be practical for your website.

aaa-text-contrast

All table headers should define a valid `scope` attribute, which tells assistive technologies
what the header refers to.

For example:

```html
<table>
    <thead>
    <tr>
        <th scope="col">Name</th>
        <th scope="col">Age</th>
    </tr>
    </thead>
    <tbody>
    <tr>
        <td>Bob</td>
        <td>35</td>
    </tr>
    <tr>
        <td>Sue</td>
        <td>45</td>
    </tr>
    </tbody>
</table>
```

In this example, the `scope` attribute indicates the two `<th>` cells are column 
headers, which allows assistive technologies to read out those headers alongside
each `<td>` cell. 

Without this information, the structure of the table is only apparent to people
who are able to see it.

add-scope-attribute-to-table-headers

All interactive components on a page, such as buttons or fields, should ideally be large enough 
to be easily used by people with motor impairments. 

This ensures people with motor impairments can easily click or tap on the element.

The recommended size is 44 x 44 CSS pixels, with some exceptions:

* **Equivalent available** - the functionality provided by
  the control is available elsewhere, and large enough, on the same page.
* **Inline text** - the control appears inside a sentence or block of text. 
* **User Agent control** - the size of the target is determined by the user agent 
  and is not modified by the author. Generally this is not the case for web content.
* **Essential** - the size of the target is essential to the information being conveyed,
  e.g. a tutorial demonstrating what a small button looks like. This exception is rare.

## Applying this check

Nearly all websites will fail this check by default. The minimum size requirement
is larger than most links and controls on most websites.

This is the much stricter version of the WCAG 2.2 AA check for target size. Most websites
should focus on the AA check before considering this AAA check:

* [Target Size (Minimum)](https://w3c.github.io/wcag/understanding/target-size-minimum.html)

## Methodology

This check is run on both the mobile and desktop versions of every page. Results
for each may differ.

1. All interactive elements are identified, including buttons, links, and form controls. 
2. If an element is preceded or followed directly by a non-empty text node, the control
   is ignored.
3. If an element is not normally visible, it is ignored. This includes elements which 
   are positioned offscreen or cropped (e.g. for 'screen-reader only' text).
4. If an element is a link, and another visible link on the page points to the same URL, with 
   that other link meeting the size requirements, the element is ignored.
5. Otherwise, the element must have a minimum size of 44 x 44 CSS pixels.

## Troubleshooting

Silktide only records the first 100 instances of a failure on a page. Because failures
of this check are common, it is possible that your page has more than 100 failures, but
only the first 100 will be shown.

## Further reading

* [Target Size (Enhanced)](https://www.w3.org/WAI/WCAG22/Understanding/target-size-enhanced)

ensure-reasonable-target-size

When viewed on small screens (like mobile phones) content should be large enough to 
read without being zoomed-into and scrolled in two dimensions.

WCAG 2.1 specifically requires this for:

+ Vertical scrolling content at a width equivalent to 320 CSS pixels
+ Horizontal scrolling content at a height equivalent to 256 CSS pixels

This issue almost always indicates that the webpage has not been designed
to work on mobile devices at all.

extreme-zoom-scrolling

All frames must define a readable title, which briefly described the contents of that frame.

Note that this is not the same as a `<title>` tag inside the iframe, which is insufficient.
You must provide a meaningful description for the frame using the `title` attribute.

Examples:

```html
<iframe title="Advertisement" src="ad.html">
```

```html
<frame title="Advertisement" src="ad.html">
```

# Why this matters

Accessible technologies such as screen readers rely on the `title` attribute to list
the frames on a given page. 

Without a title, it is impossible to know what the frame contains, and the user must
navigate inside it, and explore the contents of the frame to figure this out.

Often iframes are used for technologies like banner ads, videos, or chat widgets. The 
absence of a `title` makes these areas of the page much harder to identify, understand, 
or use.

# How titles are tested

Frames which are not presented to screen readers are ignored. This includes invisible
frames, and frames marked with `aria-hidden`.

A `title` attribute must contain meaningful text, e.g. numbers / letters, to be considered
valid. A title containing just spaces, or non-readable text (e.g. an emoji) will
be flagged as invalid.

# More information

Learn about [Technique H64](https://www.w3.org/WAI/WCAG21/Techniques/html/H64)
as part of [SC 2.4.1 - Bypass Blocks](https://www.w3.org/WAI/WCAG21/Understanding/bypass-blocks).

has-frame-title

Avoid opening links in a new tab or window. Where you must do this, include an explanation
in the text of the link.

## Why this matters

Opening links in a new tab or window breaks the back button and can be disorientating for 
novice web users, and the visually impaired. Generally you should avoid opening links in a
new tab or window, but if you have to, you should include text explaining that this will happen.

## How to fix

An explanation must be clear in the accessible text for the link. For example:

```html
<a href="products.html" target="_blank">
    Products (opens in new window)
</a>
```

Or, for an image inside a link:

```html
<a href="products.html" target="_blank">
    <img src="products.jpg" alt="Products (opens in new window)">
</a>
```

Rather than updating all of your links manually to do this, you can add a simple CSS
selector, such as:

```css
a[target="_blank"]:after {
    content: " (opens in new window)";
}
```

Note that doing this with an icon, is not sufficient to pass this check. The text must be
readable by screen readers.

Alternatively you can override the link text for accessible technologies (like screenreaders),
so that the appearance of the link does not change. For example:

```html
<a href="products.html" target="_blank" aria-label="Products (opens in new window)">
    Products
</a>
```

Note that if you do this, the `aria-label` will replace the text content of the link completely,
so it must still make sense in isolation.

## Terminology

Although it is common to say "opens in new window", almost all browsers now use tabs, and
so this terminology is potentially confusing. You may prefer: "opens in new tab".

## Methodology

1. Silktide considers all links on a page with a `target` attribute of `_blank`.
2. For each link, Silktide considers the screen-readable text of the link, which includes:
   * The text content of the link
   * Any `alt` text inside any images inside the link
   * Any `aria-label` or `aria-labelled-by` text
   * The `content` of the pseudo-elements `:before` and `:after`
3. This text is analysed for the presence of common text, including "opens new tab"
    and "opens new window". If the text is not found, the link fails the test.

## Further reading

Generally best practice is to avoid opening links in a new tab or window.  

The W3C provides detailed guidance on 
[when opening a link in a new window may be appropriate](https://www.w3.org/TR/WCAG20-TECHS/G200.html).

link-text-explains-open-in-new-window

Lists (e.g., `<ul>` or `<ol>`) should only contain list items (`<li>`) as a direct descendant 
to ensure that screen readers can accurately report the amount of items contained in the list. 

## Example

In the following example, some screen readers would say this list has two items, instead of 
four: 

```html
<ul>
    <div class="some_class">
        <li>Example 1</li>
    </div>
    <div class="some_other_class">
        <li>Example 2</li>
        <li>Example 3</li>
        <li>Example 4</li>
    </div>
</ul>
```

To fix this, you would need to remove the `<div class="some_class">` and 
`<div class="some_other_class>` elements and ensure only `<li>` list items remain.

## Further reading

The [formal specification for the list element](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/ul)
shows what is and is not permitted inside an `<ul>` and `<ol>`.

See [Technique H88](https://www.w3.org/TR/WCAG20-TECHS/H88.html) for more information.

list-not-following-semantics

Form controls must appear sufficiently distinct from their surroundings, so that people 
with visual impairments are still able to clearly see them.    

Either the border or the form control itself must have a 3:1 colour contrast with the 
surrounding area. 

## Methodology

* All `<input>`, `<textarea>`, and `<select>` elements are checked.
* For `<input>` elements, these types are ignored as their
  appearance is controlled by the browser or operating system:
  `checkbox`, `radio`, `submit`, `reset`, `image`, `hidden`, `file`. 
* The flattened background color of the control is determined. This is the color of the
  control itself, combined with any parent elements if the control is transparent.
* If the control has a border or outline:
  * The flattened background color of each edge is determined. 
    This is the color of the edge itself, combined with any parent elements
    if the edge is transparent.
  * If any edge has sufficient contrast with the flattened background color of the control, 
    the control is considered to have sufficient contrast.
* If the control does not have a border or outline:
  * The flattened background color of the surrounding 
    area is determined. This is the color of the first control's parent element which is at least 
    one pixel larger around the element in every dimension, i.e. above, below, left, and right.
  * If the background color of the element has sufficient contrast with surrounding area color
    the control is considered to have sufficient contrast.

## Troubleshooting

There are some limitations to the contrast checker:

* The use of drop shadows, glowing effects, gradients, and other complex effects 
  mean there is no one clear color to determine the contrast ratio against. 
  In these cases, the contrast ratio cannot currently be determined.
* It is possible for an element to be positioned over multiple elements, e.g. via
  `position: absolute` or `position: fixed`. In this case, the contrast ratio cannot 
  currently be determined.

## Further reading

* [WCAG 1.4.11](https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast.html)

non-text-contrast

Ensures that headings in PDF documents follow a logical hierarchical order for accessibility.

## What this means

Headings in a PDF should be arranged in a logical sequence, much like a table of contents in a book. This means using a consistent hierarchy of heading levels (like Heading 1 for main titles, Heading 2 for subsections, etc.). Headings should not skip levels abruptly (e.g., jumping from Heading 1 directly to Heading 3).

## Why it matters

1. **Accessibility**: Screen readers rely on a logical heading structure to navigate content, making it essential for users with visual impairments.
2. **Readability and Navigation**: A well-structured document with logically ordered headings enhances readability and allows all users to navigate the content more efficiently.
3. **Consistency and Professionalism**: Logical heading order reflects a professional approach to document creation and helps maintain consistency across documents.

## How to fix

1. **Review Heading Levels**: Check your document to ensure that headings follow a sequential order without skipping levels.
2. **Modify Headings**: If any headings are out of order, adjust them using your PDF editing tool to align with the logical structure.

## Testing Methodology

Silktide's checks your PDF to identify the sequence of headings. It flags PDFs where the heading order is not 
hierarchical (e.g., a Heading 3 directly following a Heading 1).

Headings in a PDF should follow the sequence Heading 1 > Heading 2 > Heading 3 without skipping intermediate headings.
It is acceptable to 'go back' to previous styles/headings but the sequence should then continue without missing headings.

### Limitations
- **Contextual Analysis**: Silktide might not fully grasp the context behind the document's structure, so manual review is recommended for complex documents.
- **Styling Variations**: Variations in styling that are not properly tagged might not be detected accurately.

## Further Reading

- [Understanding WCAG: Headings and Labels](https://www.w3.org/WAI/WCAG21/Understanding/headings-and-labels.html)
- [How to Organize PDF Content with Accessible Headings](https://www.adobe.com/accessibility/pdf/pdf-accessibility-overview.html)

pdf-headings-order

Ensure that PDF documents specifies headings for accessibility.

## What this means

Specifying headings in a PDF involves clearly defining tagged heading elements within 
the document. These headings are used to structure the content, similar to how headings 
are used in web content (like HTML). 

## Why it matters

1. **Accessibility**: Headings are crucial for screen readers and other assistive technologies. They allow users with visual impairments to navigate the document more easily.
2. **Document Structure**: Clearly defined headings help in organizing the content, making it more understandable and navigable for all users.
3. **Search Efficiency**: Proper headings improve the document's searchability, enabling users to find information more quickly.

## How to fix

1. **Use Styles in Document Creation**: When creating a document, use heading styles (like Heading 1, Heading 2, etc.) in your word processor before converting it to a PDF.
2. **Edit Existing PDFs**: If your PDF is already created, use a PDF editor to add or modify heading tags. Ensure that the headings are in a logical hierarchical order.

## Testing Methodology

Silktide flags PDFs that don't contain a single tagged heading.

## Further Reading

- [WCAG PDF9](https://www.w3.org/TR/WCAG20-TECHS/pdf.html#PDF9)
- [Creating Accessible PDFs](https://www.adobe.com/accessibility/pdf/pdf-accessibility-overview.html)
- [PDF Accessibility - Defining PDF Accessibility](https://www.webaim.org/techniques/acrobat/)

pdf-missing-headings

Ensure each PDF document has a formally defined title.

## What this means

A PDF title, typically found in the document properties, acts as the official name of the document. This title is used by screen readers and other assistive technologies to provide a clear understanding of the document's content at the outset. It's different from any title or heading text that might appear within the content of the PDF itself.

## Why it matters

1. **Accessibility**: Screen reader users often hear the document title first when they open a PDF. A clear, descriptive title helps them understand what the document is about.
2. **Searchability and Organization**: A proper title makes it easier to search for and organize documents on a computer or network.

## How to fix

1. **Set the Title in Document Properties**: In your PDF editor, access the document properties section and ensure there is a title that accurately reflects the content of the PDF.
2. **Use Descriptive Titles**: Avoid vague titles. Instead, choose titles that clearly and concisely convey the subject or purpose of the document.

## Testing Methodology

Silktide checks the document properties of a PDF to verify that a title is 
specified and not empty.

### Limitations
- **Title Relevance**: While Silktide can detect the presence of a title, it does not evaluate the title's relevance or accuracy in representing the document's content.

## Further Reading

- [WCAG - PDF 18](https://www.w3.org/TR/WCAG20-TECHS/PDF18.html)
- [Setting Titles in PDF Documents](https://www.adobe.com/accessibility/pdf/pdf-accessibility-overview.html)

pdf-no-title

When viewed on small screens (like mobile phones) content must fit without 
requiring scrolling in two dimensions.

WCAG 2.1 specifically requires this for:

+ Vertical scrolling content at a width equivalent to 320 CSS pixels
+ Horizontal scrolling content at a height equivalent to 256 CSS pixels

Except for parts of the content which require two-dimensional layout for usage or meaning,
such as a maps application.

two-dimensional-scrolling

wcag-22.score

wcag-22-a.score

wcag-22-aa.score

wcag-22-aaa.score

website.pages

website.documents

Tables which contain information should have clear headers defined.  

In this example, the top row of the table is a header:

| Surname        | City          |
| -------------- | ------------- |
| Washington     | London        |
| Phoenix        | Arizona       |
| Austin         | Travis        |

Notice how without the header here, it would be almost impossible to understand 
what the individual values mean ("Washington" could be a city or a surname). 

It is not enough to just make the headers look differently, as accessible technologies will not 
recognize this (for example, a screen reader cannot 'see' different colors or fonts). 
Table headings must be defined using the `<th>` tag. 

This example shows how a table should use a `<th>` to mark cells as headings. Note the 
use of the `col` attribute, to specify these headings are for the _column_:

```html
<table>
  <tr>
    <th scope="col">First name</th>
    <th scope="col">City</th>
  </tr>
  <tr>
    <td>Washington</td>
    <td>London</td>
  </tr>
  <tr>
    <td>Phoenix</td>
    <td>Arizona</td>
  </tr>
  <tr>
    <td>Austin</td>
    <td>Travis</td>
  </tr>
</table>
```

Tables which are used purely for layout do not need to do this. However, 
[the use of tables for layout is strongly discouraged](https://www.lifewire.com/dont-use-tables-for-layout-3468941).
This check will ignore tables that it believes are purposely used for layout.

Learn more about [accessible table design (W3C)](https://www.w3.org/WAI/tutorials/tables/one-header/).

add-header-to-tables

Radio buttons or check boxes with the same name attribute must be contained
within a fieldset element.

contain-radio-or-checkbox-with-same-name

All controls on the page - including links, buttons, and fields - should clearly 
indicate when they have been selected by the keyboard.

This is a stricter version of [WCAG 2.4.7](https://www.w3.org/WAI/WCAG21/Understanding/focus-visible.html),
which requires that the focus indicator is visible, but doesn't specify how clearly
it should be visible.

You can confirm this yourself by loading a webpage and using the Tab key to navigate 
through it. Anything you can select should clearly alter its appearance when selected. 
For example, a text field might change color, or have a distinctive border applied. 

## The requirements

The [official requirements](https://w3c.github.io/wcag/understanding/focus-appearance.html) are 
complicated. A simplified version is:

* Surround the control with a solid outline
* The outline must have at least 3:1 contrast with its background
* The outline must have at least 3:1 contrast with its surroundings, or be at least 2px thick

The actual requirements allow for more variation, but generally require that you 
calculate the perimeter and/or area of the focus area, which can be very difficult.

## How to fix

Links and form controls should use a focus selector which contrasts with their
unfocused state, as well as any surroundings of the focus state. 

In practice, the easiest way to accomplish this is to use a two-color focus, like so:

```css
/* ensure high-contrast mode still has an indicator */
outline: 2px transparent solid;

/* Apply a thick yellow box-shadow with 
   a thin dark blue indicator in the middle */
box-shadow: 0 0 0 2px #F9F9D1, 0 0 0 4px #396196, 0 0 4px 8px #F9F9D1;
``` 

From [Technique C40](https://www.w3.org/WAI/WCAG22/Techniques/css/C40).

Using two contrasting colors guarantees that the focus state will be visible, 
regardless of the background or surrounding colors.

## Troubleshooting

### Not enough contrasting pixels change

The [Success Criterion](https://w3c.github.io/wcag/understanding/focus-appearance.html) specifies a minimum area 
for the contrasting portion of the focus indicator, which is equivalent to a 2 CSS pixel border around the component.

From the requirements:

> "The easiest and most common way to meet this requirement is to use a solid outline around the component. 
> The outline must be at least 2px thick."

In practice, many websites use alternatives to this, such as a thick border along one edge. A problem with 
that approach is it is often dependent upon the length of that one edge, which for text links can vary dynamically.

See [Sara Soueidan](https://www.sarasoueidan.com/blog/focus-indicators/#2.-minimum-contrasting-area) for a good
write-up of this concept.

To comply with this Success Criterion, we recommend adding a 2px border around all edges.

Note an earlier draft of this Success Criterion has a more generous allowance here, which is not the case for the
final version.

### Elements appear to change in the browser

Focus states should be defined in CSS alone, and not require JavaScript to work. 

Try disabling JavaScript on the page, and see if focus is still visible. If it not, 
then the focus state won't work with assistive technologies that don't have a physical
keyboard, e.g. mobile phones.

Some more unusual means of implementing a focus state cannot be detected or measured
automatically. These include:

* Focus implemented via pseudo-elements - such as `::after` or `::before`. 
* Focus using `:focus-within` (JavaScript current provides no way to access these).
* Focus cascaded to child elements, e.g. a `<span>` inside an `<a>` tag. We detect
  some of these cases, but there are variations that we cannot detect.

Currently, there is no practical way to assess these focus states automatically.

### Elements over images not analyzed

Silktide cannot assess the contrast of elements that are over images. This is because
the contrast of an element is calculated by comparing the color of the element with the
color of the background. 

If the element is over an image, the background color is the
color of the image, which varies from pixel-to-pixel, and may vary further as the page
is resized, due to responsive design.

### Unexpected elements are focusable

You may be surprised to see tags like `<div>` or `<span>` being shown as focusable.
If an element has a `tabindex` of 0 or higher, it becomes focusable. Any HTML tag can be made 
focusable in this way, this is so that custom controls (e.g. your own drop-down menus, or 
sliders) can support keyboard navigation. [Learn more about tabindex on MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex).

## Further reading

* [WCAG 2.4.13](https://www.w3.org/WAI/WCAG22/Understanding/focus-appearance.html)
* [Minimum Contrasting Area explained (Sara Soueidan)](https://www.sarasoueidan.com/blog/focus-indicators/#2.-minimum-contrasting-area)

ensure-focus-appearance

All controls on the page - including links, buttons, and fields - should show when 
they have been selected by the keyboard.

You can confirm this yourself by loading a webpage and using the Tab key to navigate 
through it. Anything you can select should alter its appearance when selected. 
For example, a text field might change color, or have a distinctive border applied. 

This is default behavior for all standard web controls, and so if this issue is appearing
it is because this default behavior has been disabled. Or alternatively, if you have written
your own custom controls, these will need styling to support focus states.

## How to fix

Links and form controls typically define an `outline` CSS style, which ensures
they are highlighted automatically, for example:

```css
input:focus (outline: 2px solid red);
``` 

If you choose to override or disable the default `outline`, you should specify an accessible 
alternative, such as a border or background color.

### Elements appear to change in the browser

Focus states should be defined in CSS alone, and not require JavaScript to work.

Try disabling JavaScript on the page, and see if focus is still visible. If it not,
then the focus state won't work with assistive technologies that don't have a physical
keyboard, e.g. mobile phones.

Some more unusual means of implementing a focus state cannot be detected or measured
automatically. These include:

* Focus implemented via pseudo-elements - such as `::after` or `::before`.
* Focus using `:focus-within` (JavaScript current provides no way to access these).
* Focus cascaded to child elements, e.g. a `<span>` inside an `<a>` tag. We detect
  some of these cases, but there are variations that we cannot detect.

Currently, there is no practical way to assess these focus states automatically.

### Unexpected elements are focusable

You may be surprised to see tags like `<div>` or `<span>` being shown as focusable.
If an element has a `tabindex` of 0 or higher, it becomes focusable. Any HTML tag can be made 
focusable in this way, this is so that custom controls (e.g. your own drop-down menus, or 
sliders) can support keyboard navigation. [Learn more about tabindex on MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex).

## Further reading

* [WCAG 2.4.7](https://www.w3.org/WAI/WCAG22/Understanding/focus-visible.html)

ensure-focus-is-visible

All interactive components on a page, such as buttons or menus, should be far enough apart 
from other interactive areas, to avoid them being used by mistake. 

This ensures people with motor impairments can easily click or tap on the right element.

## How to fix

* Ensure all interactive elements are at least 24 CSS pixels wide and tall
* OR ensure there is at least 24 CSS pixels (minus the width and height of the element)
  between each interactive element

## Methodology

This check is run on both the mobile and desktop versions of every page. Results
for each may differ.

1. All interactive elements are identified, including buttons, links, and form controls.
2. If an element is not normally visible, it is ignored. This includes elements which
   are positioned offscreen or cropped (e.g. for 'screen-reader only' text).
3. If an element is larger than 24 CSS pixels in both dimensions, it passes.
4. Otherwise, the element is compared to all other elements on the page.
5. The minimum horizontal gap between the element is calculated as 24 CSS pixels,  
   minus the width of the element.
6. The minimum vertical gap between the element is calculated as 24 CSS pixels,  
   minus the height of the element.
7. If another element falls within the minimum horizontal or vertical gap, the 
   element fails, unless both are links that point to the same place.

## Further reading

* [Target Size (Minimum)](https://www.w3.org/WAI/WCAG22/Understanding/target-size-minimum.html)
* [Technique C42 - Using min-height and min-width to ensure sufficient target spacing](https://www.w3.org/WAI/WCAG22/Techniques/css/C42)

ensure-minimum-target-size

People using screen readers are not able to see the layout of a form. To make forms
accessible, they must define explicit text labels for each form control. 

Usually the best solution is to use a `<label>` element. The label may be linked to 
by the form control:

```html
<label for="name">Full name</label>
<input type="name" id="name">
```

or the `<label>` can be wrapped around the form control:

```html
<label>
    Full name <input type="name">
</label>
```

Buttons are different, as their labels are specified by the code for the button, e.g.

```html
<input type="submit" value="Send message">
<button>Send message</button>
```

Alternatively ARIA attributes, such as `aria-label` may be used, but this information
will not be conveyed to visual users. For more information, see [W3C's guide to labeling controls](https://www.w3.org/WAI/tutorials/forms/labels/).

Hidden input fields (`<input type="hidden">`) do not require labels.
Note that the `placeholder` attribute 
[should not be used as an alternative to a label](https://www.w3.org/TR/html/sec-forms.html#the-placeholder-attribute),
nor should the `title` attribute.

## Custom roles

Note that this check considers the underlying accessible role of an element, which can be 
different from the tag itself.

For example, this `<div>` has a `role` of `button`, and so is expected to have a label, like
a button would.

```html
<div role="button"></div>
```

form-control-labels

Every page should precisely specify what language(s) it is written in. 

## Why this matters

Screen readers, which read out the text on a page, need to know the language to 
pronounce it correctly. Without the language, text may sound like gibberish. 

For example: imagine a computer pronouncing just one German word
"die" (pronounced "dee") using English pronunciation. Now extend that to every
word on the page.

Search engines may also use the language to classify pages, so this can have
an effect on SEO as well.

## How to fix

The `<html>` element should have a `lang` or `xml:lang` attribute which describes 
the language of the page.

You will usually want to use the `lang` attribute as follows:

```html
<html lang="en-US">
```

(Note this example won't work for XHTML, which is deprecated and highly discouraged).

Make sure you specify a [valid language code](http://www.rfc-editor.org/rfc/bcp/bcp47.txt).

## More information

See [Technique H57](https://www.w3.org/TR/2016/NOTE-WCAG20-TECHS-20161007/H57).

html-lang-required

An `<img>` element inside a link must not specify alternative text that duplicates the
content of a text link inside or beside it.

For example, this code should be avoided:

```html
<a href="/apple">
    <img src="apple.png" alt="Apple">
    Apple
</a>
```

Accessible technologies will tend to see this as "Apple Apple". The correct behaviour is to
specify either a null (empty) `alt` attribute:

```html
<a href="/apple">
    <img src="apple.png" alt="">
    Apple
</a>
```

or to hide the image via `aria-hidden`:

```html
<a href="/apple">
    <img src="apple.png" aria-hidden="true">
    Apple
</a>
```

# Learn more

Read about [Technique H2](https://www.w3.org/TR/WCAG20-TECHS/H2) on how to combine
an adjacent image and texts links. 

See the [WAI Tutorial on decorative images](https://www.w3.org/WAI/tutorials/images/decorative/).

img-duplicate-alt

The purpose of a link should be clear from the text inside the link. Links like "learn more" are
not helpful to users with assistive technology.

Links should also avoid redundantly saying that they are links, e.g. "link to page" as screen
readers will read these out with the word "link" added, e.g. "link link to page".

Exceptions to these rules are allowed where the purpose of a link would be ambiguous to users 
in general.

link-purpose-a

Lists of related items should be written [semantically](https://html.com/semantic-markup/) as a 
list.

Usually this means rewriting these to use the `<ul>` or `<ol>` tags.

This allows assistive technologies to more easily navigate from item to
item, or past entire groups of links if the user wants to. 

## Examples 

### Navigation

This navigation:

```html
<a href="/about">About us</a>
<a href="/products">Products</a>
<a href="/contact">Contact us</a>
```

Should be rewritten as a list:

```html
<ul>
  <li><a href="/about">About us</a></li>
  <li><a href="/products">Products</a></li>
  <li><a href="/contact">Contact us</a></li>
</ul>
```

### Tables for content

This single-column table is redundant. There is no
value in placing the content in a table, which makes
it harder for screen reader users to interpret and interact
with.

```html
<table>
  <tr>
    <td>
      Banana
    </td>
  </tr>
  <tr>
    <td>
      Apple
    </td>
  </tr>
  <tr>
    <td>
      Pear
    </td>
  </tr>
</table>
```

Should be rewritten as a list:

```html
<ul>
  <li>Banana</li>
  <li>Apple</li>
  <li>Pear</li>
</ul>
```

## Justification

Users of assistive technologies, like screen readers, can skip an entire
list in one step. In some cases, they can even search inside a list. 

These aids are not available where links are written outside a list. 
Failing to use lists correctly can force users to have to step through
hundreds of items one at a time.

## Methodology

1. Any single-column tables are automatically considered 
   redundant lists. 
2. For non-table elements, recursively work down the page looking inside
   each element for links separated by minimal amounts of non-link text. 
   If the non-link text is below 30 characters 
   in length, we assume we're inside content that should be a list.
   Some exceptions are made, e.g. the presence of an `<hr>` would break
   out of the list.

## More information

See [Technique
H48](https://www.w3.org/TR/2016/NOTE-WCAG20-TECHS-20161007/H48) for
details.

mark-navigation-section-as-list

Every page should have a clearly defined heading, known as a "H1" (Heading 1).

A `H1` is the main heading of the page. It helps accessibility by allowing uses to
skip to the main content of the page. It helps all users identify what the page is about. 
It helps SEO by giving special emphasis to the topic of the page.

It is not enough to simply include large text. Headings must be coded 
[semantically](https://html.com/semantic-markup/) as `<h1>` tags, like so:

```html
<h1>This is a heading</h1>
```

Note that headings must contain some machine readable text to be considered valid. 
For example, this heading is not valid:

```html
<h1>
    <img src="company-logo.png">
</h1>
``` 

But with the addition of `alt` text, this heading is valid:

```html
<h1>
    <img src="company-logo.png" alt="About Company Inc.">
</h1>
``` 

Generally we recommend you just use plain text for your headings.
See [Technique H42](https://www.w3.org/TR/WCAG20-TECHS/H42) for more details.

missing-h1

Links must be defined in a specific way to be accessed by screen readers, which are used by 
blind and the partially-sighted.

To work with accessibility technologies, links must contain both machine-readable text, and 
a `href` attribute. If a link is not actually
pointing to a page or part of a page, it should be replaced with another semantic element, such
as a `button`, or the `<a>` tag should have a role of `button`. 

For example:

```html
<a href="/about">About us</a>
```

If the link contains _nothing but an image_, that image should specify alternative text, e.g.

```html
<a href="/apple">
    <img src="apple.png" alt="Apple">
</a>
```

Before HTML5, an anchor was often used to create a target to link to, e.g.

```html
<a name="example"></a>
```

This is not supported in HTML5, and the use of anchors for targets is discouraged. Use an `id`
attribute on a non-anchor tag instead, e.g.

```html
<div id="example"> ... </div>
```

Empty links (e.g. `<a></a>`) are often incorrectly used for buttons or controls in a
JavaScript application. In these cases, you should usually define the link as having a more appropriate
role, e.g. as a button. To do this, use the `role` attribute (e.g `<a role="button">`), or replace 
the `<a>` tag with a more appropriate tag, such as `<button>`.

For more details, see [Technique H91](https://www.w3.org/TR/2016/NOTE-WCAG20-TECHS-20161007/H91)
and learn about [ARIA roles](https://www.sitepoint.com/how-to-use-aria-effectively-with-html5/).

Priority	Recommendation	Progress
	Ensure pages don't scroll in two dimensions on small screens WCAG 2.1 AA 1.4.10	43.7%
	Ensure PDFs have a title WCAG 2.0 A 2.4.2	0%
	Ensure pages don't require zooming and 2D scrolling on small screens WCAG 2.1 AA 1.4.10	95.8%
	Ensure links explain they open in a new tab WCAG 2.0 AAA 3.2.5	2%
	Ensure lists are marked up correctly WCAG 2.0 A 4.1.1	90.6%

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