For the purposes of the enactments mentioned in section 27, the development plan for any area in Wales shall be taken as consisting of—
the provisions of the unitary development plan for the time being in force for that area, together with a copy of the relevant local planning authority's resolution of adoption or of the Secretary of State's notice of approval or, where part of the plan has been adopted and the remainder approved, copies of the resolution and the notice; and
any alteration to that plan, together with a copy of the relevant local planning authority's resolution of adoption, or the Secretary of State's notice of approval, of the alteration or, where part of the alteration has been adopted and the remainder approved, copies of the resolution and the notice.