Area-based exemption admissibility: ownership changes, relocation, and adjacent expansion preserve residual exemption subject to safeguards. The Board confirms the area-based exemption attaches to the Unit: change of ownership does not forfeit the residual exemption if the new owner opts in writing before first clearance; relocation within specified areas preserves residual exemption subject to inventorisation and Chartered Engineer certification that plant, machinery and manpower have been shifted within the notified area; and expansion by acquiring adjacent land and installing new plant and machinery is treated like on-plot expansion and remains eligible for the residual exemption period.