16 Obsolete features16.1 Obsolete but conforming features16.1.1 Warnings for obsolete but conforming features16.2 Non-conforming features16.3 Requirements for implementations16.3.1 The marquee element16.3.2 Frames16.3.3 Other elements, attributes and APIs16 Obsolete features 16.1 Obsolete but conforming features Features listed in this section will trigger warnings in conformance checkers. Authors