Allow global configuration of the volume of all rendered audio, with an option to override audio volumes specified by the author or user agent defaults.
As part of satisfying provision one of this checkpoint, allow the user to choose zero volume (i.e., silent).
Normative inclusions and exclusions
This checkpoint must be satisfied for all implemented specifications that produce sound; see the section on conformance profiles.
Conformance profile labels: Audio
Conformance detail: For both content and user agent