The Local Government (Planning and Development) Act 1993, brought development by or on behalf of State authorities within the planning system. Section 4 (1)(g) of the Local Government (Planning and Development), Act 1963 provides that the alteration of an existing structure, where the external appearance is not materially affected, is exempted development. S.I. No. 78 of 1997, made by my predecessor on 12 February 1997, clarified section 4(1)(g) and provided that the attachment to an existing radio mast of antennae for mobile telephony and the replacement of an existing mast would, subject to certain criteria, be exempted development. These regulations apply equally to radio masts owned by public authorities or private bodies.