A low-level accessibility compliance requirement with numerous components, the most basic of which are a definition, an evaluation function, and result messages. When a rule is evaluated, it is assigned a rule result value.
The set of HTML elements to which a particular rule applies. This may include a pseudo-element identified as page, which is a placeholder for the document element. When a rule is evaluated, each of its target resources is assigned an element result value.
A set of rules that embodies specific standards compliance goals. Each rule within a ruleset is designated as either required or recommended, according to its relationship to the compliance goals of the ruleset.
The application of all evaluation functions of all rules in the selected ruleset to their corresponding target resources in a web page, and the subsequent collection of all evaluation results and messages, at both the rule and element levels, into a dataset.
The aggregate result of a rule evaluation with respect to its target resources (all of its target elements and/or the entire page).
The result of a rule evaluation with respect to one of its target elements.
The scope helps the developer understand what they need to consider in satisfying a rule.
Element level rules require looking at element's features for content, labeling, properties and states.
Page level rules require looking at the page to help users understand the purpose and structure of the content on a page.
Website level rules require looking at the set of pages in a website for consistent ordering and labeling of content and making sure users understand the unique content of each page through effective titling of the pages.