Guidance on reviewing green belt boundaries is set out in Planning Policy Guidance Note 2: Green Belts, issued in 1995. Guidance on environmental assessment of Regional Spatial Strategies is included in ‘Sustainability Appraisal of Regional Spatial Strategies and Local Development Documents’, issued in 2005. Regional Spatial Strategies set the framework for green belt policy, including the direction of long-term development in a region. They may include policies to review green belts, but it is for the local planning authorities to determine any detailed changes to green belt boundaries.