A rule is the description of the procedure used to evaluate the status (pass or fail) of one ore more conditions of a requirement in a given context.

The rule defines:

  • the context in which it is applicable (e.g. a set of elements in a DOM)
  • a set of assumptions about the environment (e.g. the way in which technologies are used)
  • a set of logical steps to carry out the procedure
  • a set of possible results


A test is the application of a rule.


A requirement is a statement of necessity in a given domain (e.g. accessibility). It can be broken down into a set of conditions.