2.23 Create documents that validate to published formal grammars
Contents
WAI Checkpoint 3.2
Full WAI text: "Create documents that validate to published formal grammars."
An HTML document's mark-up must follow the rules which are set out in a formal set of mark-up declarations which are contained in a published formal grammar or Document Type Definition (DTD).
Rationale
Documents that are created using published formal grammars will be supported by more browsers and assistive technologies.
Many accessibility features of assistive technology, accessible web technology, and web browsers rely on published formal grammars. Failing to work to a formal published grammar may make a web page directly inaccessible or inaccessible to assistive technologies like screen readers, Braille devices, etc. Writing code which validates to formal grammars also facilitates indexing tools, search engines, programs that extract tables to databases, navigation tools that use header elements and automatic text translation software.
Directions and Techniques
Include a document type declaration referring to a published DTD
Use the DOCTYPE statement as the first line of your HTML file for the particular grammar (e.g. the strict HTML 4.0 DTD) that the code adheres to.
Refer to the WAI recommended techniques for this guideline
See the WAI recommended techniques for creating documents that validate
How you could check for this:
Test with the W3C HTML validator
The W3C HTML validator can check HTML to ensure that it validates to formal grammars. The W3C also provide a comprehensive list of the formal grammars which it uses. Some authoring tools also include validators. If you use an authoring tool, you should ensure that the validator is up to date.
Guidelines for Web Accessibility - Priority 2- 2.1 Ensure that images have sufficient contrast for people with colour deficient vision
- 2.2 Avoid causing content to blink
- 2.3 Avoid movement in content
- 2.4 Ensure that dynamic content is accessible or provide an alternative presentation or page
- 2.5 Use style sheets to control layout and presentation
- 2.6 Use relative rather than absolute units
- 2.7 Use header elements to convey structure
- 2.8 Break up large blocks of information where appropriate
- 2.9 Ensure that information laid out using tables make sense when linearised, or provide an alternative equivalent
- 2.10 Do not use structural mark-up to format information laid out using tables
- 2.11 Describe the purpose of frames and how they relate to each other if it is not obvious by their titles alone
- 2.12 Clearly identify the target of each link
- 2.13 Provide information about pages and sites in metadata
- 2.14 Provide information about the general layout of a site
- 2.15 Use navigation mechanisms consistently
- 2.16 Associate labels explicitly with their controls
- 2.17 Properly position the labels of form controls
- 2.18 Ensure that user interfaces are device-independent
- 2.19 Use logical event handlers in scripts
- 2.20 Use input device-independent event handlers in scripts and applets
- 2.21 Ensure that scripts and applets are accessible
- 2.22 When an appropriate markup language exists, use markup rather than images to convey information
- 2.23 Create documents that validate to published formal grammars
- 2.24 Mark up lists and list items using the proper HTML tags
- 2.25 Use quotation mark-up for quotations, but not for formatting
- 2.26 Where possible, use appropriate W3C technologies of the latest supported versions
- 2.27 Avoid deprecated features of W3C technologies
- 2.28 Do not periodically auto-refresh pages
- 2.29 Do not use mark-up to redirect pages automatically
- 2.30 Do not generate pop-ups or other windows and do not change the current window without informing the user
