4. Any reference (express or implied) in any enactment, instrument or document to—
(a)a rewritten provision, or
(b)things done or falling to be done under or for the purposes of a rewritten provision,
is to be read as including, in relation to times, circumstances or purposes in relation to which any corresponding superseded provision had effect, a reference to the superseded provision or (as the case may be) things done or falling to be done under or for the purposes of the superseded provision.