This Part applies for the purposes of any step which may be or is required to be taken in relation to a joint development plan document as it applies for the purposes of any step which may be or is required to be taken in relation to a development plan document.
For the purposes of subsection (1) anything which must be done by or in relation to a local planning authority in connection with a development plan document must be done by or in relation to each of the authorities mentioned in section 28A(1) in connection with a joint development plan document.
If the authorities mentioned in section 28A(1) include a London borough council or a Mayoral development corporation, the requirements of this Part in relation to the spatial development strategy also apply.
Those requirements also apply if—