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Maasdriel

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

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

When selecting a user interface component with the keyboard, the focus indicator must 
not be _partly_ obscured by anything in front of it. 

## Why this matters

When using a keyboard, it is important that the user can see where they are on the page.
If the focus indicator is obscured, the user may not know where they are, and may not
be able to interact with the page.

## Examples

Most common examples include:

* Banners at the top or bottom of the page, such as cookie banners
* Fixed navigation bars
* Fixed footers
* Popup modals, such as cookie consent modals

## Testing this manually

* Open the page
* Press the tab key to move focus through elements on the page
* Check that the focus indicator is not fully obscured by anything in front of it

## Comparison with Level AA version

This is the stricter (Level AAA) version of the Level AA check (2.4.11).

The Level AA version only flags issues where the focus indicator is _completely_ obscured, this
version flags issues where the focus indicator is _partly_ obscured.

## How to fix

With elements that cover part of the screen, such as cookie banners, ensure
that the user can scroll to see any content behind the banner, without having to close
the banner.

The two most very common solutions are:

1. Avoid the use of fixed elements that could obscure other elements
2. Use the CSS `scroll-margin` property (see [WCAG Technique C43](https://www.w3.org/WAI/WCAG22/Techniques/css/C43))

With popup modals, it should usually be impossible to focus anything behind the modal.
Most common modal frameworks will automatically trap focus within the modal, so that
this is impossible. Example: [Bootstrap Modal](https://getbootstrap.com/docs/5.2/components/modal/#live-demo).

## Methodology

1. Silktide simulates a keyboard user tabbing through the page
2. Silktide simulates the focused element being vertically scrolled into the center of the page
   (see 'Rationale for scrolling' below)
3. For each element that receives focus, Silktide checks that the focus indicator is not obscured
   by another element on top of it
4. If the focus indicator is obscured, Silktide raises an issue

### Rationale for scrolling

The rationale for point #2 (above) is worth expanding. At different screen sizes, the amount of scrolling
a browser makes between tabs will vary. For example, Chrome will typically avoid scrolling until a
focus element falls outside the current viewport, and then it will adopt the least amount of
scrolling possible to bring the element into view.

This means if you test a page in Silktide, and in a browser with a fractionally different height,
you may experience different elements being obscured or not, especially elements blocked by sticky headers
and footers. Every only a few pixels of difference in screen height can make a huge difference the
further down the page you go.

In all these cases, the use of user-directed vertical scrolling, e.g. via the cursor keys, would permit
the focused element to be seen. Whether that would be necessary would depend on the exact browser and
size of the browser viewport.

Silktide purposely adopts a generous frame here, to avoid flagging issues which might only affect the
exact screen size that it tested. In our testing, when we didn't do this, the number of subjectively false
positives could be very high, and extremely confusing, as they would not replicate during manual testing on
anything but the exact same browser size.

Essentially, Silktide chooses not to flag issues which _could_ affect some very particular screen sizes
_inconsistently_, but it will flag issues that should affect _all_ screen sizes consistently.

The W3C does not specify how to test this Success Criterion.

### Simulating conditional modals

Silktide adopts additional behavior to simulate the use of dialog modals that may be opened by user
behavior after a page loads (i.e. modals that don't automatically open when a page loads).

If a non-opened modal is detected, Silktide assumes that _elements outside the modal cannot be focused_.
This is not guaranteed, but it is impossible for Silktide to predict the behavior of a modal that has not
yet been opened, and this is much more accurate than assuming that the modal does not constrain focus.

As a result, a modal which is incorrectly programmed (i.e. doesn't constrain focus) may not be detected
as obscuring focus behind it, if the modal is not opened by default.

## Further reading

* [WCAG 2.4.12](https://www.w3.org/WAI/WCAG22/Understanding/focus-not-obscured-enhanced)
* [WCAG Technique C43 - Using CSS margin and scroll-margin to un-obscure content](https://www.w3.org/WAI/WCAG22/Techniques/css/C43)

ensure-focus-is-not-obscured-enhanced

When selecting a user interface component with the keyboard, the focus indicator must 
not be _completely obscured_ by anything in front of it.

## Why this matters

When using a keyboard, it is important that the user can see where they are on the page.
If the focus indicator is obscured, the user may not know where they are, and may not
be able to interact with the page.

## Examples

Most common examples include:

* Banners at the top or bottom of the page, such as cookie banners
* Fixed navigation bars
* Fixed footers
* Popup modals, such as cookie consent modals

## Testing this manually

* Open the page
* Press the tab key to move focus through elements on the page
* Check that the focus indicator is not fully obscured by anything in front of it

## Comparison with Level AAA version

This is the less strict (Level AA) version of the Level AAA check (2.4.12).

This Level AA version only flags issues where the focus indicator is _completely_ obscured, the
Level AAA version flags issues where the focus indicator is _partly_ obscured.

## How to fix

With elements that cover part of the screen, such as cookie banners, ensure
that the user can scroll to see any content behind the banner, without having to close
the banner.

The two most very common solutions are:

1. Avoid the use of fixed elements that could obscure other elements
2. Use the CSS `scroll-margin` property (see [WCAG Technique C43](https://www.w3.org/WAI/WCAG22/Techniques/css/C43)) 

With popup modals, it should usually be impossible to focus anything behind the modal.
Most common modal frameworks will automatically trap focus within the modal, so that
this is impossible. Example: [Bootstrap Modal](https://getbootstrap.com/docs/5.2/components/modal/#live-demo).

## Methodology

1. Silktide simulates a keyboard user tabbing through the page
2. Silktide simulates the focused element being vertically scrolled into the center of the page
   (see 'Rationale for scrolling' below)
3. For each element that receives focus, Silktide checks that the focus indicator is not obscured
   by another element on top of it
4. If the focus indicator is obscured, Silktide raises an issue

### Rationale for scrolling

The rationale for point #2 (above) is worth expanding. At different screen sizes, the amount of scrolling 
a browser makes between tabs will vary. For example, Chrome will typically avoid scrolling until a
focus element falls outside the current viewport, and then it will adopt the least amount of 
scrolling possible to bring the element into view.

This means if you test a page in Silktide, and in a browser with a fractionally different height, 
you may experience different elements being obscured or not, especially elements blocked by sticky headers 
and footers. Every only a few pixels of difference in screen height can make a huge difference the 
further down the page you go.

In all these cases, the use of user-directed vertical scrolling, e.g. via the cursor keys, would permit 
the focused element to be seen. Whether that would be necessary would depend on the exact browser and
size of the browser viewport.

Silktide purposely adopts a generous frame here, to avoid flagging issues which might only affect the 
exact screen size that it tested. In our testing, when we didn't do this, the number of subjectively false
positives could be very high, and extremely confusing, as they would not replicate during manual testing on
anything but the exact same browser size.

Essentially, Silktide chooses not to flag issues which _could_ affect some very particular screen sizes 
_inconsistently_, but it will flag issues that should affect _all_ screen sizes consistently.

The W3C does not specify how to test this Success Criterion.

### Simulating conditional modals

Silktide adopts additional behavior to simulate the use of dialog modals that may be opened by user
behavior after a page loads (i.e. modals that don't automatically open when a page loads).

If a non-opened modal is detected, Silktide assumes that _elements outside the modal cannot be focused_.
This is not guaranteed, but it is impossible for Silktide to predict the behavior of a modal that has not
yet been opened, and this is much more accurate than assuming that the modal does not constrain focus.

As a result, a modal which is incorrectly programmed (i.e. doesn't constrain focus) may not be detected 
as obscuring focus behind it, if the modal is not opened by default.

## Further reading

* [WCAG 2.4.11](https://www.w3.org/WAI/WCAG22/Understanding/focus-not-obscured-minimum)
* [WCAG Technique C43 - Using CSS margin and scroll-margin to un-obscure content](https://www.w3.org/WAI/WCAG22/Techniques/css/C43)

ensure-focus-is-not-obscured-minimum

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

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

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

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

wcag-22.score

wcag-22-a.score

wcag-22-aa.score

wcag-22-aaa.score

website.pages

website.documents

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

Priority	Recommendation	Progress
	Ensure PDFs have a title WCAG 2.0 A 2.4.2	0%
	Ensure focus is not fully obscured WCAG 2.2 AA 2.4.11	88.8%
	Ensure interactive components are far enough apart WCAG 2.2 AA 2.5.8	60.4%
	Ensure lists are marked up correctly WCAG 2.0 A 4.1.1	97.3%
	Ensure focus is not partly obscured WCAG 2.2 AAA 2.4.12	79%

Maasdriel

Accessibility

WCAG Levels

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