Digital Content Standards

Web Content Accessibility Guidelines (WCAG)

Web Content Accessibility Guidelines (WCAG) standards are the most commonly used standards that are mandated in many countries’ legal requirements. They are all based on 4 design principles:

Perceivable - you have to be able to perceive all available content with senses the end user possesses
Operable - you have to be able to use all available content with different interfaces the end user can use
Understandable - you have to be able to understand all available content and how to access it with the ability the end user has
Robust - you have to be able to use the content in an interoperable and compatible way with third party technologies the end user can use

WCAG has different versions that appear in various legislations across the world.

The UK requires 2.2, which was released in October 2023
The EU requires a standard similar to 2.1 (called EN 301 549 Annex A). WCAG 2.1 was released in June 2018
The US requires 2.0, which was released in December 2008. WCAG 2.0 is identical to ISO/IEC 40500:2012

Generally each version includes everything from the previous one, and adds extra, making them all backwards compatible. Between 2.0 and 2.1 there were 17 additions, and between 2.1 and 2.2 there were 9 additions, and 1 removal (this is Parsing, which has become obsolete). Therefore you could interpret this as the newer version therefore being stricter, higher standards.

The WCAG guidelines are split into 3 levels that increase in strictness, A, AA and AAA, with A being basic or minimum accessibility with 25 success criteria, AA strong with an additional 13 criteria (38 total) and AAA outstanding with an additional 23 criteria (61 total). AA is the default level that is captured in legislative requirements, and reaching WCAG A will not make a digital resource legally compliant. Some aspects of AAA are not applicable in many situations.

The WCAG standards are split into 13 guidelines, that are further split into more detailed success criteria - the number of success criteria depends on the WCAG level.

Count	WCAG Guideline Number	WCAG Guideline Title
1	1.1	Text Alternatives
2	1.2	Time Based Media
3	1.3	Adaptable
4	1.4	Distinguishable
5	2.1	Keyboard Accessible
6	2.2	Enough Time
7	2.3	Seizures and Physical Reactions
8	2.4	Navigable
9	2.5	Input Modalities
10	3.1	Readable
11	3.2	Predictable
12	3.3	Input Assistance
13	4.1	Compatible

More information on the success criteria is available here:

Web Content Accessibility Guidelines - Quick Reference

Web Content Accessibility Guidelines in Plain English

The full details of each version of WCAG are available here:

Web Content Accessibility Guidelines (WCAG) 2.2 AA

Web Content Accessibility Guidelines (WCAG) 2.1 AA

Web Content Accessibility Guidelines (WCAG) 2.0 AA

EN 301 549 Annex A

EN 301 549 Annex A is the standard required to be compliant with EU legislation, and it is roughly similar to WCAG 2.1 AA. It has a broader scope than WCAG (which just covers websites), and includes all ICT products and services in the public sector, including specific requirements around web sites and documents that are both part of the website (HTML or embedded) or downloadable from them (called Non-web Documents).

It includes the same 4 design principles of Perceivable, Operable, Understandable and Robust, and the requirements are mapped to WCAG and directly reference them. This includes the requirements around Non-web Documents, which are described separately to the requirements for Websites.

WAI-ARIA

Web Accessibility Initiative - Accessible Rich Internet Applications (WAI-ARIA) provides an ontology of roles, states, and properties that define accessible user interface elements and can be used to improve the accessibility and interoperability of web content and applications. Accessibility of web content requires semantic information about widgets, structures, and behaviours, in order to allow assistive technologies to convey appropriate information to persons with disabilities. These semantics are designed to allow an author to properly convey user interface behaviours and structural information to assistive technologies in document-level markup.

WAI-ARIA provides Web authors with the following:

Roles to describe the type of widget presented, such as “menu”, “treeitem”, “slider”, and “progressbar”
Roles to describe the structure of the Web page, such as headings, and regions
Properties to describe the state widgets are in, such as “checked” for a check box, or “readonly” for most form controls
Properties to define live regions of a page that are likely to get updates (such as stock quotes)
A way to provide keyboard navigation for the Web objects and events, such as those mentioned above