The defining of Conservation Areas is governed by the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997; an update from previous Acts relating to such areas. Conservation Areas are designated by local planning authorities and can play an important role in environmental enhancement, economic and community regeneration (e.g. Townscape Heritage Initiatives and Conservation Areas Regeneration Schemes). Councils review conservation areas from time to time in order to assess the need for alteration of boundaries for areas for which special planning considerations apply, e.g. Article 4 directions. Many conservation areas now have character appraisals to explain what it is that should be preserved and what can be enhanced.