xmlns:atom="http://www.w3.org/2005/Atom"
4. For the purpose of paragraph 3—
(a)“powered support” means a support which is advanced and set to the roof by mechanical energy;
(b)“beam” means that part of a powered support system designed to be set to the roof; and
(c)“immediate forward support system” means a system of supports designed to be advanced and set to the roof immediately after extraction by a coal-getting machine.