Accessibility WCAG 2.0 Validation Rules

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Contents 1 Links to OpenAjax Rules Grouped By WCAG 2.0 Principles 2 Rule Information and Abbreviations 2.1 Rule ids 2.2 Severity Levels 2.3 Priority Levels

Links to OpenAjax Rules Grouped By WCAG 2.0 Principles

• Rules for Principle 1 Perceivable
• Rules for Principle 2 Operable
• Rules for Principle 3 Understandable
• Rules for Principle 4 Robust

Rule Information and Abbreviations

The accessibility validation rules enumerated in this document directly support WCAG 2.0, some with reference to the Document Object Model (DOM) and some with reference to the WAI-ARIA specification and WAI-ARIA best practices. Rules are divided according to the four principles of WCAG 2.0:

1. Perceivable - Information and user interface components must be presentable to users in ways they can perceive
2. Operable - User interface components and navigation must be operable
3. Understandable - Information and the operation of user interface must be understandable
4. Robust - Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies

Within each section representing a WCAG 2.0 principle is a table that contains:

1. the guideline number, linked to that guideline in WCAG 2.0
2. the success criterion
3. the list of validation rules that apply to that criterion along with a suggested rule id for each rule
4. a suggested violation level for each rule
5. relevant techniques for implementing the success criterion or passing the given rules

For more information about the structure of WCAG 2.0 and an explanation of principles, guidelines, success criteria, and techniques, see WCAG 2.0 Layers of Guidance. Also, note that this document currently restricts itself to A and AA compliance for WCAG 2.0. Future work may include validation rules for AAA-level success criteria.

Although this document enumerates rules that directly support WCAG 2.0, there is no reason that the rule logic for evaluating each rule could not be reused in testing the items in other checklists. Indeed, one of the chief aims of this task force is to produce reusable rule objects that are readily-consumable and to help tool vendors avoid duplicating rule logic.

Rule ids

The rule ids used in this document are only suggestions but will be used within the group to identify particular rules mentioned on this page, in related documents, and to be found in the rules repository. Rule ids are taken from an assigned range of numeric values based upon the contributing organization. (See the Accessibility_Validation_Rule_Codification_Requirements for more information.) The importance of an id is to identify a piece of rule logic that, when executed successfully, indicates only that the test embodied by that rule has been passed. Most tool vendors and open-source tool developers will already have their own rule ids in place or an algorithm for adding other rule ids. Again, the hope is that rule logic will be reused and that the use of WCAG 2.0-oriented rule ids in this document does not discourage this practice.

Severity Levels

Only one of the following violation levels may be returned by a rule for a node in the document:

Violation (V)

Indicates a direct violation of a success criterion or undermines a technique for implementing a success criterion

Recommendation (R)

Indicates direct violation of or non-conformance to a best practice

Potential Violation (PV)

A condition for a potential violation has been met

A manual test is required to determine if success criterion have been met

Potential Recommendation (PR)

A condition for a potential recommendation has been met

A manual test is required to determine if best practice has been met

Warning (W)

Coding practice that is suspicious, but is not necessarily a violation

Hidden (H)

Content that is hidden from a rendering that is important for meeting an accessibility requirement

A node would have been evaluated by an accessibility rule, but since it was hidden it was not evaluated

Pass (P)

requirement was met

As in the case of rule ids, The above violation levels are only suggestions but will be used throughout this document to indicate the impact to a piece of content or to an application of a particular rule's failing. Tool venders are free to map these levels to their own violation levels and to add additional violation levels as they see fit.

Priority Levels

Only one of the following priorities levels may be assigned to a rule in this document. Priority levels are relative to each other for a requirement, so Priority 1 items should be addressed before Priority 2 items, and Priority 2 items before Priority 3 items.

Priority 1 (P1)

If there are multiple violations on the page, the Priority 1 items should be addressed first

Priority 2 (P2)

If there are multiple violations on a page, Priority 2 should be addressed after all Priority 1 violations have been eliminated

Priority 3 (P3)

If there are multiple violations on a page, Priority 3 should be addressed after all Priority 2 violations have been eliminated