(1) For this part, a scheme includes all or part of--
(a) a contract, agreement, arrangement, understanding, promise or undertaking (including all steps and transactions bringing it into effect)--
(i) whether entered into or made orally or in writing; and
(ii) whether express or implied; and
(iii) whether or not enforceable; and
(b) a plan, proposal, action, course of action or course of conduct, whether unilateral or otherwise; and
(c) a trust.
(2) A reference in this part to a scheme includes a reference to any part of the scheme.