The HTMLMediaElement.defaultMuted property reflects the muted HTML attribute, which indicates whether the media element's audio output should be muted by default. This property has no dynamic effect. To mute and unmute the audio output, use the muted property.
The HTMLModElement interface provides special properties (beyond the regular methods and properties available through the HTMLElement interface they also have available to them by inheritance) for manipulating modification elements, that is <del> and <ins>.
The HTMLObjectElement interface provides special properties and methods (beyond those on the HTMLElement interface it also has available to it by inheritance) for manipulating the layout and presentation of <object> element, representing external resources.
The HTMLObjectElement.typeMustMatch property is a Boolean reflects the typemustmatch attribute of the <object> element and indicates if the resouce linked by it must match the MIME type given by HTMLObjectElement.type in order for this resource to be used.
The HTMLOListElement interface provides special properties (beyond those defined on the regular HTMLElement interface it also has available to it by inheritance) for manipulating ordered list elements.