Paragraph 4
Where there is a substantial change in the operation of an existing Part A installation on or after 31st October 1999 and before the transitional date, the prescribed date for that part of the installation affected by the change shall be–
where an application for a permit authorising the operation of that part of the installation is duly made before the transitional date, the determination date for that part of the installation;
where no such application is made, the transitional date.
Where there is a substantial change in the operation of an existing Part A installation on or after the transitional date, the prescribed date for that part of the installation affected by the change shall be the date on which the change is made if earlier than the date which would be the prescribed date for the installation under paragraph 2.