Interface properties are declared using interface-property-declarations: interface-property-declaration : attributesnewtypeidentifier{interface-accessors}interface-accessors : attributesget;attributesset;attributesget;attributesset;attributesset;attributesget; The attributes, type, and identifier of an interface property declaration have the same meaning as those of a property declaration in a class (17.6). The accessors of an interface property declaration correspond to the accessors of a class property declaration (17.6.2), except that the accessor body must always be a semicolon. Thus, the accessors simply indicate whether the property is read-write, read-only, or write-only.